:?:-x-Nv ■
HARVARD MEDICAL LIBRARY
RONTGEN
THE LLOYD E. HAWES
COLLECTION IN THE
HISTORY OF RADIOLOGY
^Harvard Medical Library in the Francis A. Countwav Library of Medicine Boston
veritatem per MedicijsTAM QUyERAMUs
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HIGH-FREQUENCY CURRENTS
HIGH-FREQUENCY CURRENTS
BY
FREDERICK FINCH STRONG, M.D.
Instructor in Electro-Therapeutics at Tuft 's College Medical School, Boston.
WITH 183 ILLUSTRATIONS IN THE TEXT
NEW YORK
REBMAN COMPANY
1123 BROADWAY
Copyright, 1908, by
REBMAN COMPANY
New York
Entered at Stationers' Hall, London, England, 1908
A 11 rights reserved
Printed in America
PREFACE
In all ages of which we have any authentic knowledge, and among all races, there have existed Philosophers, Investigators or Students of the Occult, who have in divers forms, and many languages, repeatedly averred that the Universe — both visible and invisible — exemplified varied expressions of a single prin- ciple— Vibration. During the last two centuries we have abandoned the theoretical and hypothetical science of the Ancients, and have gradually built up a coherent fabric by logical deductions from actual study of the facts and phenomena of the objective world. Up to a few decades ago, the various truths postulated by science had not fully conformed to a con- dition of "harmonious correlated Unity," which theoretically should be the case according to Herbert Spencer. The Chemical Elements were apparently distinct, unalterable, and bore no mathematical relation to each other. Seventy or more varieties of solid indivisible atoms formed the basis of the material uni- verse, and behind these was a hypothetical "Ether" of abso- lutely unknown nature. Matter was called "dead," or "living," according to the reflected phenomena, and an apparently bound- less gulf existed between the two. Science was becoming more and more complex when the advance guards of a new era appeared, headed by Clerk Maxwell with his "Electro-magnetic Theory of Light," and Mendelejeff with his "Periodic Law of the Elements," and rapidly followed by Crookes, Tesla, Curie, Becquerel, Hertz and J. J. Thompson, whose labors and re- searches have focused in the greatest discovery of any age — The Electron Theory. Although recent and revolutionary, this hypothesis has met with instant and eager acceptance on the part of the leading scientists throughout the world. In the bright light which it throws on the phenomena of the universe, much that was dark and undefined has become lucid and coher-
vi PREFACE
ent. All sciences have become united by invisible links, and we have for the first time in the history of the world a complete, harmonious system of natural philosophy, by which all facts of nature, however diverse, may be co-related and traced to a common origin. And the crowning postulate of this wonderful new system is identical with the most ancient theory of the universe which history records. In other words science in- forms us that all natural phenomena result from Vibration in a medium of a primitive nature, which appears to be nothing more nor less than Electricity. All forms of Force, from the attraction of the Sun for the Earth to the vital phenomena of the Human Organism, are fundamentally Electrical Vibrations.
The "High-frequency Currents" are Electrical Vibrations artificially produced, which bear a certain relation to the cur- rents which traverse the nerves in the maintenance of life in the human body. Being Vibrations, rather than flowing streams of Electrical particles, the High-frequency Currents penetrate glass as readily as a sound wave would traverse a plate of metal, and pass through the human organism without producing the slightest sensation.
The discovery and application of High-frequency Currents has resulted mainly from the work of two American Scientists, Tesla and Elihu Thomson. Tesla first recognized the won- derful therapeutic possibilities of High-frequency Currents and prophesied that they would ultimately supersede the older systems based upon the therapeutic use of Drugs ; clinical results recorded during the past five years go far to confirm the accuracy of Testa's prophecy.
Although a greater part of the literature of High-frequency Therapeutics ascribes the development of these currents for the treatment of disease to ,d' £rsonval and Oudin, it is, la fact of record that the subject was developed independently by the present writer on distinctly different lines. Whereas d'Arson- val's work was solely with Low Potential Currents, while Oudin 's High-potential effects were of Mono-polar character and there- fore limited to the treatment of local conditions — the writer from the very first employed the Bipolar High-potential Cur- rents of Tesla, and it is due to this fact that the System of Tech-
PREFACE Vll
nic developed by him for the therapeutic application of Tesla Currents possesses so much wider a field of usefulness and produces so many more distinct physiological effects than the methods developed by Oudin and d'Arsonval. For the past decade the writer has been continuously engaged in a clinical and laboratory study of the various types of High-frequency Currents; hundreds of cases have been treated, and many im- portant facts recorded, which are given to the profession for the first time in the present volume.
At the request of a number of his colleagues the present writer has not only gone into minute details in connection with the physical laws and methods of using the various apparatus herein described, but has compiled a concise Elementary Text- book containing the Essentials of the entire subject of Electro- therapeutics. This little book, which is a pocket-edition, should be carefully studied as a preliminary introduction to the present volume.
In conclusion, the writer desires to acknowledge his indebt- edness for the help which he has obtained from the works of Freund, Belot, Guilleminot and Chisholm Williams. He also extends his hearty thanks for the collaboration and valuable assistance accorded him by Dr. H. G. Piffard, Professor Elihu Thomson, Dr. J. P. Sutherland and Professor Northrop. Valu- able clinical information has been received from a number of physicians, for which due acknowledgment will be made in the Treatise on the Therapeutic results of High-frequency Treatment, which the writer purposes to compile during the next two years, as a more or less necessary sequel or comple- ment to the present volume.
TABLE OF CONTENTS
CHAPTER I
PAGE
Historical and Introduction ...... 1
CHAPTER II
Electrons and Vibration ...... 18
Table of Waves of Radiant Energy . . . .24
CHAPTER III
Electro-Physics, from the Standpoint of the Electron
Theory 30
Magnetism . . . . . . . . .33
CHAPTER IV
Electro-Physics {continued)
The Nature and Generation of Alternating Currents . . 36
CHAPTER V
Physical Factors Involved in the Generation of High-
Frequency Currents ...... 46
CHAPTER VI
European Types of High-Frequency Apparatus . . 58
CHAPTER VII
The Development of American High-Frequency Thera- peutics Earlier Forms of Alternating Current Apparatus . . 88
TABLE OF CONTENTS
CHAPTER VIII
PAGE
Modern High-Frequency Apparatus op the American Type
Tesla-Thomson Coils . . . . . - 106
CHAPTER IX
Modern American High-Frequency Apparatus, for
"Direct Current" Use . . . . . .114
CHAPTER X
Analysis and Comparison of High-Frequency Currents
of Different Forms of Apparatus . . . 124
CHAPTER XI
The Phenomena and Physical Properties of High-
Frequency Currents (^4.) Phenomena of Induction
(B) Electro-Static Phenomena
(C) Electro-Dynamic Phenomena
(D) Resonance Effects .
. 132
. 133
. 135
. 142
. 146
CHAPTER XII
The Measurement of High-Frequency Currents . . 149
CHAPTER XIII
Technic for the Therapeutic Application of High- Frequency Currents ...... 155
CHAPTER XIV
Therapeutic Technic {continued)
The Resonator Discharge . . . . . .161
CHAPTER XV
Therapeutic Technic (continued)
Methods for the Application of Tesla Currents . .166
TABLE OF CONTENTS XI
CHAPTER XVI
PAGE
Therapeutic Technic {continued)
Treatment by Means of Glass " Vacuum Electrodes" . . 175
(A) Monopolar Direct Application 185
(B) Monopolar Indirect Application 186
(C) Bipolar Direct Application 186
(D) Bipolar Multi-Frequency Treatment 187
CHAPTER XVII
The High-Frequency Current for the Production of
the X-Ray .190
CHAPTER XVIII
The Generation of the Ultra-Violet Ray by High- Frequency Currents . . . . . .201
CHAPTER XIX
The Generation of Ozone by the High-Frequency
Current ..... ... 205
CHAPTER XX A Review of Modern Therapeutic Methods . . 209
CHAPTER XXI
Physiological Action of Oscillatory Currents . .216
CHAPTER XXII
The Therapeutic Action of High-Frequency Currents 226
(A) D'Arsonval Currents ...... 227
(B) Currents of Very High Potential with Relatively Low Amperage ........ 229
1. Monopolar Treatment . . ... 230
2. Bipolar Application or Tesla Technic . . . 238
3. Multi-Frequency Modalities ..... 242
4. Hyperstatic Technic ...... 247
Xll
TABLE OF CONTENTS
CHAPTER XXIII
PAGE
High-Frequency Currents in the Treatment of Diseases
of Nutrition ........ 249
(A) Diseases of the Digestive System .... 250
(B) Diseases of the Blood and Heart .... 253
(C) Diseases of the Respiratory Tract .... 255
Pulmonary Tuberculosis ..... 257
(D) Diseases Involving Deranged Metabolism . . . 268
(E) Diseases of the Excretory Apparatus . . . 270
CHAPTER XXIV
ThE Treatment of Diseases of the Nervous System by
High-Frequency Currents ..... 272
CHAPTER XXV
Infectious and Malignant Diseases
275
CHAPTER XXVI
Special Uses for Currents of High Frequency
INDEX
280
285
LIST OF ILLUSTRATIONS
1. Arrangement of Ley den Jars for Producing Alternating
Currents of Great Frequency. (D'Arsonval-Hertz.) . 5
2. D'Arsonval Auto-Conduction Cage; Upright Form.
(Piffard's.) 6
3. D'Arsonval Auto-Condensation Couch. (Williams.) . 7
4. Miniature Tesla Apparatus. (E. Ducretet.) . . 7
5. Diagram of Oudin-D'Arsonval High-frequency Appar-
atus ......... 8
6. Small " Tesla," or " Secondary" Coil for Use with Pri-
mary Solenoid ....... 8
7. D'Arsonval Bipolar High-tension Coil. (Williams.) . 9
8. Diagram of Solenoid and Resonator. (Freund.) . . 10
9. Oudin Resonator. (Williams.) . . . . .11
10. Bipolar Resonator of O'Farril . . . . .11
11. Rochefort's Bipolar Resonator. (Guilleminot.) . .11
12. Piffard's "Hyperstatic Transformer" . . . .12
13. The Author's Air-gap Condenser Terminals . . 16
14. A System of Technic for the Therapeutic Use of
High-frequency Currents . . . . .17
15. Schematic Diagram Showing Spontaneous Degenera-
tion of Atoms ....... 22
16. Magnetism Induced in Iron Bar by Current in Coil of
Wire . . . 33
17. Diagram Indicating Wave Length and Frequency of
Known Forms of Radiant Energy . . . .35
18. Hydraulic Analogue of " Continuous Current" Circuit . 36
19. Hydraulic Analogue of " Alternating Current " Circuit . 37
20. "Graphic Tracing" of Alternating (Sinusoidal) Current 37
21. Magnetic-electric Induction. (Williams.) .
22. Diagram of Simple "Magneto", Generating an Alter
nating Current ......
23. )
' [-Leyden Jar, or Condenser
24
40
40 43
xiv LIST OF ILLUSTRATIONS
FIGURE PAGE
25. Plate Condenser with Inductance Coil and Discharging
Circuit 44
26. Diagram Showing Analogy Between Falling Water and
a Current of Electricity. (Williams.) . . .47
27. Plate I. D'Arsonval Circuit and Hydraulic Analogue . 48
27. Plate II. Tesla-Thomson Circuit and Hydraulic Ana-
logue ......... 49
28. Bursting and He-formation of Elastic Skin on Boiling
Molasses ........ 51
29. Bursting and Re-formation of Elastic Skin on Boiling
Molasses ........ 51
30. Sir Oliver Lodge's Hydraulic Analogue . . .54
31. Electrolytic Interrupter of Wehnelt. (Williams.) . 58
32. Noden Valve, or Rectifier. (Williams.) . . .59
33. Ruhmkorff Induction Coil. (Watson, London.) . . 60
34. Ruhmkorff Induction Coil, Shown Diagrammatically.
(Williams.) 61
35. Mercury Jet Interrupter. (Isenthal & Co.) . . 62
36. Dipper Mercury Interrupter . . . . .63
37. Mackenzie-Davidson Interrupter . . . .63
38. Wehnelt Interrupter. (Williams.) . . . .64
39. Oudin-Dean Resonator. (Williams.) . . .65
40. Resonator of Lebailly and O'Farril . . . .67
41. Rochefort's Bipolar Resonator. (Freund.) . . 67
42. Upright Solenoid on Cabinet. (Williams.) . . 68
43. Isenthal-Oudin Resonator . . . . . 69
44. Gaiffe's Oil Condenser and Heavy Solenoid . . .71
45. Gaiffe's Bipolar Resonator . . . . .72
46. Condenser. (From Belot.) . . . . .73
47. Liquid Resistances. (From Belot.) . . . .74
48. Arrangement of Valves, Tube and Meter. (From Belot.) 75
49. Transformer. (From Belot.) . . . . .76
50. General Diagram. (From Belot.) . . . .77
51. Top Shelf of Cabinet. (From Belot.) . 78
52. Lower Shelf of Cabinet. (From Belot.) . . .78
53. Springs and Contact Plate. (From Belot.) . . 79
54. Regulating Apparatus Arrangement of Transformer.
(From Belot.) ....... 80
55. Isenthal's Complete High-frequency Apparatus.
(Williams.) ....... 81
LIST OF ILLUSTRATIONS
XV
56. 57.
58.
59.
60. 61. 62. 63. 64. 65. 66. 67. 68. 69. 70. 71. 72. 73. 74. 75. 76. 77. 78.
79.
80. 81.
82. 83.
84. 85. 86.
Resonator and Condensers (small model). (Williams.) 82
Diagram of the Author's Original Type of High-fre- quency Apparatus; "The Strong-Ovington Coil"
"The Knott" High-frequency Coil, Working Part Im- mersed in Oil .......
Diagram of the Author's Apparatus, Adapted for the Generation of Heavy D'Arsonval Currents, as well as those of the High-potential ("Tesla") Type .
Kinraide Coil; Alternating Type
Diagram of Kinraide Coil Showing Relation of Spirals
Tesla-Thomson High-frequency Apparatus
Piffard's "Hyperstatic Transformer"
Brown High-frequency Coil
Campbell High-frequency Coil .
Kinraide Coil with Improved Spark-gap
Cyclone Coil. (Portable form.)
Spark-gap of Jackson Coil
High-frequency Spark-gap
The Author's "Special Hercules" Coil
Jackson Coil with Separate Secondaries
The Author's "Ajax Coil"
The "Ajax Special Coil"
Theater Plug
The Author's New Graduated Spark-gap, for Ajax Coils 110
The Author's "Hercules" High-frequency Apparatus 111
The Author's Improved Rotary Spark-gap
Rotary Converter, Excited by a 110-Volt Direct Cur- rent, and Generating an Alternating Current of 80 Volts
Scheidel-W'estern Coil for Exciting High-frequency Apparatus ......
" Scheidel- Western " High-frequency Apparatus
" Inducto-resonator " Involving Induction, as well as Resonance .
"Meyrowitz" High-frequency Apparatus .
The "Cole Coil" for X-Ray and High-frequency Gene ration .......
The Hercules "Universal"
The Author's Improved Electrolytic Interrupter
The High-frequency Discharge .
83
84
85
88
89
90
92
94
95
96
98
102
102
103
104
107
108
109
112
115
116 117
117
118
119 121 122 125
Xvi LIST OF ILLUSTRATIONS
FIGURE PAGE
87. Graphic Tracings of High-frequency Currents . . 125
88. Arrangement for the Production of Oudin-D'Arsonval
Currents .....••• 126
89. Arrangement for the Production of Tesla-Thomson Cur-
rents ......-•• 127
90. Graphic Representations of Various Currents . . 128
91. Lamp Lighted by the Current "Backed Up" by the
Impedance of the Heavy Copper Arch Attached to the D'Arsonval Solenoid ..... 134
92. Incandescent Lamps lit by Currents Induced in Closed
Circuits 134
93. Geissler Tube Illuminated on the "Electrical Aura"
or "Vibratory Field" Surrounding a Patient, con- nected to a Terminal of a Tesla Coil . . . 135
94. Beautiful Efhuve from the Points of a Skeleton Star . 136
95. Illuminated Sign, Formed by the Effluve Given from a
Fine Wire . . . ..-.'■ • • • 137
96. Terminals of the Author's Apparatus Arranged to
Show the "Arc" Discharge ..... 137
97. Primary Condenser Discharges per Second . . 138
98. Appearance of Rapidly Revolving Narrow Geissler
Tube Connected to Terminal of "Ajax Coil" . . 139
99. "Pseudo-Static Spark" from the Author's Hercules
Machine 140
100. Resonator Discharge from Terminal of Tesla Coil . 142
101. Flow of a High-frequency Current Through a Wire
to an Insulated Metal Plate .... 144
102. The Author's Apparatus for Demonstrating the Elec-
tro-dynamic Phenomena of High-frequency Currents 145
103. Autograph of a Pair of Artery Forceps Laid Upon a
Sensitive Plate . . . . . . .147
104. Hot Wire Milliampere Meter for Measuring the Inten-
sity or Volume of Currents of High-frequency . 150
105. Lamp Bulb Hand-Electrode ..... 151
106. The Author's Photometric Mil-ammeter . . . 152
107. Professor Flemming's Direct Reading Cymometer."
(Marconi Wireless Telegraph Co.) . . . 153
108. Direct Treatment by Current from D'Arsonval Sole-
noid Applied to Patient, Through Sponge-covered Electrodes . . . . . . . .156
LIST OF ILLUSTRATIONS XV11
FIGURE PAGE
109. Auto-conduction Cage — Horizontal Form . . . 156
110. Piffard's Improved Auto-Conduction Cage. Vertical
Form ........ 157
111. Small Cages for Treatment of Arm, Leg, etc. . . 158
112. Condenser Couch. (Williams.) . . . .158
113. Piffard's " Cushion Spiral" 159
114. Piffard's "Condenser Chair" 160
115. Effluve Electrodes 163
116. "High-frequency Cautery" ..... 164
117. Tesla-Effluve 168
118. "Pseudo-static Spark" Treatment . . . .169
119. High-frequency "Motor- Wave Current" . . .170
120. The Author's Mechanism for Superimposing a Low-
frequency, Sinusoidal Wave Upon a Tesla Current 171
121. High-frequency Motor-Impulse Current. (Pseudo-
Faradic.) 172
122. Theoretical Tracing of Current Obtained by the Use
of the Author's Mechanical Device . . . 173
123. Theoretical Tracing of Current Obtained by the Use
of the Author's Mechanical Device . . . 173
124. The Author's Technic for Vacuum Electrodes. "Tesla
Vacuum Treatment" ...... 176
125. Doctor Snow's set of Vacuum Electrodes . . 180
126. Double-walled Vacuum Electrodes . . . . 181
127. The Author's Technic for the Use of Glass Condenser
Electrodes 182
128. The Author's Regulating Handle for Vacuum or Con-
denser Electrodes . . . . . .182
129. Herschell's Regulating Handle and Rectal Electrode.
(Williams.) 182
130. Ebonite Spinal Electrode. (Williams.) . . .183
131. Condenser Electrode; "Low Red Vacuum Type" . 184
132. Vacuum Condenser Electrode with Cupping Device . 184
133. Monopolar Direct Technic ..... 185
134. Monopolar Indirect Technic ..... 185
135. Bipolar Direct Application of Vacuum Electrodes . 186
136. Friedlander's Vacuum Condenser Chair . . . 187
137. The Author's set of Condenser Electrodes . . 188
138. Method of Taking a "Skiagraph" . . . .193
139. X-Ray Tube with Solid Metal Anode . . .194
wiii LIST OF ILLUSTRATIONS
FICURE PAGE
140. "Water-cooled" X-Ray tube 194
141. Vacuum Regulators for X-Ray Tubes . . . 195
142. Self-regulating X-Ray Tube 196
143. Types of "High-frequency X-Ray Tubes" . . 197
144. Thomson Double Focus X-Ray Tube . . .198
145. Single Focus Tube for H. F. Currents; with Hollow
Metal Cone Under Anode 198
146. Single Focus Tube for H. F. Currents (Double Bulb
Type) 199
147. Latest X-Ray Tube for Either Direct or Alternating-
Currents ....'.-.. 200
148. Diagram of Finsen's Arc Lamp. (Guilleminot.) . 201
149. Piffard's Spark-gap Lamp ..... 202
150. Strong's Ultra-violet Lamp for Use with "Ajax" or
"Hercules" Coils 202
151. Strong's Apparatus for the Treatment of Pulmonary
Tuberculosis ....... 206
152. Apparatus for Generating Galvanic and Faradic
Currents from Battery Cells or Edison 110- Volt "Direct" Circuit 217
153. Diagram of Static Electrification . . . .218
154. "Static Breeze." (Diagram.) 218
155. Diagram of Static Spark Treatment . . .219
156. Diagram of Static Induced Current . . .219
157. Diagram of Static Wave Current .... 220
158. D'Arsonval Auto-conduction Cage Operated from the
Author's "Hercules" Coil 228
159. Diagram of "Labile" Method for Solenoid Currents . 228
160. Sponge-covered Electrodes for "Labile D'Arsonvaliza-
tion" 229
161. Piffard's Small Spiral with Condensers; for Use with
Ruhmkorff Coil 230
162. Vacuum Electrode Covered with Chamois Skin . 233
163. Ultra-violet Vacuum Lamp with Quartz Lens . . 234
164. Indirect Vacuum Treatment 235
165. Rhythmic Effluve Treatment for General Stimulation . 239
166. "Motor Impulse" Treatment 240
167. The Author's Technic for Vacuum Electrodes . . 240
168. The Author's Treatment for Diseases of the Uterus . 241
169. Double Vacuum Treatment ..... 242
LIST OF ILLUSTRATIONS XIX
FIGURE PAGE
170. Double Effluvation from the Author's Apparatus . 242
171. European Outfit for Double Effluvation, by Means of
Two Resonators ....... 243
172. The Author's " Condenser Effluve " Treatment . . 244
173. Tracing Giving a Conventional Idea of the Nature of
the Author's High-frequency Wave Current . . 245
174. Graphic Tracing Giving Theoretical Idea of the Au-
thor's Motor Impulse Current .... 246
175. Graphic Tracing Giving Theoretical Idea of "Pseudo-
faradic" Current ...... 246
176. Piffard's Technic for his "Trans-resonator Effluve" . 247
177. Piffard's Electrode for Obtaining his "Trans-resonator
Effluve" 247
178. Diagram of the Author's Treatment for Diseases of
the Intestinal Canal . . . . . .251
179. The Author's Treatment for Chronic Constipation
and for Chronic Colitis ..... 252
180. Tubulated Vacuum Electrode for Inhalation Treat-
ment ......... 257
181. The Author's Portable High-frequency Apparatus
Operated by Current from its Own Battery . 276
182. The Author's Localizing Effluve Electrode for Treat-
ing Ulcers and Septic Areas .... 277
183. Vacuum Electrodes for Treatment of Pyrrhoea Alveo-
laris .282
HIGH-FREQUENCY CURRENTS
HIGH-FREQUENCY CURRENTS
CHAPTER I
HISTOEICAL AND INTRODUCTORY
The gradual waning and ultimate extinction of the vital spark at the close of a long and healthy life must be regarded as a phenomenon quite as natural as that of birth, but we must admit that at the present day a great majority of the deaths are abnormal and premature, resulting from the adverse influences of disease and unhygienic environment. That the race will ultimately reach a stage of advancement in which physical health will be the rule and death by disease a rare event, we have reason to hope and believe from the results of hygienic education and public sanitation which have been introduced during the past few decades and which have already greatly increased the average length of life. The study of pathology and bacteriology has resulted in Antitoxic methods for the pre- vention of many formidable diseases. Surgery has become a science through the same means, while the advent of Antitoxic serum marks the first strictly scientific use of a chemical sub- stance as a curative agent. Almost all the drugs of the Materia Medica have been used in a more or less empirical manner. The study of the fundamental processes of cell action and vital chemistry has resulted in a more rational selection and prepa- ration of food and has evolved the modern science of Dietetics. Finally, after exhausting all the resources of complex indirect methods of treatment, the medical profession have begun to study the therapeutic action of the fundamental forces of nature.
Prior to the last decade, physical therapeutic agents com- prising the X-Ray, Ultra Violet Ray, Light and Sound Waves, Mechanical Vibration, Scientific Nerve Massage and the various
l
2 HIGH-FREQUENCY CURRENTS
forms of electricity were used in a desultory and unscientific manner, being absolutely ignored by a large majority of the profession. It was the advent of the Roentgen Ray which formed the entering wedge for the introduction of physical methods into therapeutics by bringing the physician into touch and familiarizing him with apparatus for the generation of electricity of much higher potential than formerly used in elec- tro-therapeutics. A physician using a Static machine for X-Ray purposes would naturally desire to know the technic whereby the various currents obtainable from his apparatus could be applied to therapeutics. Similarly at the present time, the pur- chaser of a Ruhmkorff Coil for radiography naturally investi- gates the methods of oVArsonval and Oudin, of which he can avail himself at a small expense by the addition of a "Resona- tor" to his coil. The modern High-frequency apparatus of the Tesla-Thomson type, as employed by the present writer, has been an important factor in the development of physical thera- peutics, although designed originally for radiographic use.
Prior to Roentgen's discovery, the use of electricity as a thera- peutic agent, was confined to the employment of Faradism and Galvanism by a very small percentage of the profession, the currents being as a rule seldom used except as adjuvants to some older and more conventional method of treatment. A few enthusiastic specialists, however, carried on investigations in electro-physiology and pathology and laid the foundation of our modern scientific use of electricity for the treatment of disease.
The Induction Coil, invented by Faraday in 1831, was greatly improved as a therapeutic agent by Dubois-Reymond, Triplier, and Apostoli. The convenience of the Faradic battery, its portability, and the wonder and mystery that surrounded it in the eyes of illiterate persons, led to its adoption by many quacks and irregular practitioners, whose extravagant and unwarranted claims resulted in the ostracism of electro-thera- peutics by many of the more conservative members of the profession.
Galvani's discovery (in 1790) of the response of a frog's muscle to electrical stimulation, supplemented by Volta's development of the "Voltaic Pile" (in 1800), gave us the Galvanic Current,
HISTORICAL AND INTRODUCTORY 3
which has been scientifically developed into a valuable thera- peutic agent by Remak, Rockwell, Apostoli, and others.
Its principal value lies in its power to dissolve cicatricial and redundant tissues and to drive remedial agents directly into the body. The Static Machine, which was originally employed for therapeutic purposes by Benjamin Franklin, had reached a very perfect stage of development when Roentgen's discovery was given to the world. In 1881 Dr. Wm. James Morton of New York published a report describing a new substitute for the Faradic Current, derived from the Static Machine by the use of Leyden Jars, in series with the patient. This u Static Induced Current," although in reality not of an oscillatory nature, was the prototype of our modern High-frequency Currents, and is of interest inasmuch as it marks the first use of condenser dis- charges in the treatment of disease. The discharge of the Leyden Jar or Condenser (invented in 1775 by Professor Musschen- broek) was studied in 1842 by Professor Henry of this country, who demonstrated its oscillatory nature. In 1847 Von Helm- holtz made a similar statement, which was definitely proven by the experiments of Doctor Feddersen of Denmark in 1850 by the use of the rotating mirror. The spark from the Jar was in this manner shown to consist of a series of oscillations, whose period was estimated at not less than one one-millionth of a second. In 1886, Professor Heinrich Hertz published his epoch-making discovery of Electrical Waves, which was supplemented by the work of Sir Oliver Lodge in 1887. Hertz's " Resonator" con- sisted of two polished metal spheres on the outer end of two metal rods, which terminated in small brass balls separated by a gap of fifteen millimeters. The rods were connected with the terminals of an induction coil, and the sparks between the small spheres were found to set up radiating Electrical Waves, capable of inducing sparks across a minute break in a brass wire circle suspended near the coil. The size of the circle and wire had to be very carefully determined, as the waves caused no sparks unless the circle was " tuned" to respond to a vibration of the same frequency as that of the waves. This apparatus forms the basis of modern Wireless Telegraphy as well as our apparatus for the production of High-frequency Currents.
4 HIGH-FREQUENCY CURRENTS
The peculiar physiological properties of alternating currents of High-frequency were noticed some years prior to the discovery of their remarkable physical peculiarities. In experimenting with the great Spotteswoode Coil, Ward, in 1879, found that when a frequency of 8,000 interruptions per second was attained, acci- dental shocks were much less severe than with a lower rate of interruption. Rowland, some years later found that High- frequency Currents obtained from the Leyden Jar discharge could be passed through the body with little discomfort. While Joubert, in 1889, found that a nerve-muscle preparation from a frog's leg did not respond to a rapid oscillatory current. The development of High-frequency Currents from a physical stand- point has resulted mainly from the independent investigations of two American scientists — Prof. Elihu Thomson and Nicola Tesla. In a lecture before the Royal Society of Engineers in 1891, Tesla demonstrated his wonderful discoveries in High- frequency Currents by a series of brilliant experiments. This lecture has been published in book form and was for many years the only obtainable work on this subject. At the World's Fair in 1893, Prof. Elihu Thomson exhibited his giant High-frequency Coil which produced a flaming arc of over six feet in length. Up to within a few years this was by far, the largest induction coil in the world. Despite its tremendous power, the current from this coil could be passed through the body with but little discomfort. The therapeutic development of High-frequency Currents generated in accordance with the methods of Tesla and Thomson has been almost exclusively the work of the present writer and was begun in 1895. In 1893, Professor d'Arsonval of Paris published a report of his experiments with High-frequency currents obtained from the apparatus of Hertz and Sir Oliver Lodge. He had been engaged for some years in studying the physiological effects of Sinusoidal Currents of high and low frequencies, and had noticed that the phenomenon of muscular excitation decreased progressively as the frequency was increased. His experiments are reviewed in detail in a succeeding chapter. He first used the apparatus of Hertz, 1891, obtaining a current of considerable strength and a fre- quency so high that their passage through the body was attended
HISTORICAL AND INTRODUCTORY 5
with no sensation whatever. The apparatus which he era- ployed is illustrated diagrammatically in Fig. 1. The Leyden Jars (A-A') are connected to the terminals of a powerful Static Machine or Ruhmkorff Coil ; their outer coatings (B-B') are con- nected to the ends of a coil of heavy copper wire (C-C'). The number of turns in this coil depend upon the size and capacity of the Leyden Jars, in other words, the inductance of the coil must be attuned to the capacity of the Jars or Condensers. (See chapter on Physics.) This produces electrical resonance be- tween the Jars and the Coil, so that when a spark passes between A and A', several hundreds of thousands of electrical oscillations
Fig. 1. — Arrangement of Leyden Jars for Producing Alternating Currents of Great Frequency. (D'Arsonval-Hertz.)
will pass through the coil. By connecting a wire to the termi- nals (C-C') of the coil (which is called the " Solenoid of d'Arson- val"), these oscillations can be conducted to an external circuit. When the latter is formed of two persons (D-D') holding be- tween them an incandescent bulb, L, the High-frequency Cur- rents formed by succeeding groups of electrical oscillations, will light the lamp to its full candle power. D'Arsonval states that he has been able to pass through his body currents of more than three amperes. Prof. Elihu Thomson has passed through his body without injury a current four or five times this amount. If the frequency of the above currents had been fifty, or a hun- dred, instead of from five hundred thousand, to a million per second, fatal results would have been instantly produced. The theories which have been advanced to account for the apparent
6
HIGH-FREQUENCY CURRENTS
immunity of the animal body to powerful Currents of High- Frequency will be fully discussed in the chapter on physiology. D'Arsonval observed that painless Currents of High-Frequency could be induced in the human body without actual electrical
contact. In place of the Small Solenoid, he substituted a large spiral of heavy wire wound upon a cylin- drical wooden frame- work, forming a cage in which the patient stood or reclined. (See Fig. 2.) This apparatus is used in Therapeutics under the name of the " Auto-conduction Cage of d'ArsonvaL" Another method de- vised by d'Arsonval for the application of these currents is known as "Auto-con- densation." The pa- tient is connected to one end of the Small Solenoid by a metal hand electrode, the other end of the sol- enoid being attached to a large sheet of
Fig. 2. — D'Arsonval Auto-Conduction Cage; Upright Form. (Piffard's.)
thin metal placed upon the couch upon which the patient reclines; a thick cushion covered with heavy sheet rubber is interposed between the plate and the patient, and may be regarded as analogous to the insulating glass of a Ley den Jar, the inner and outer coatings of which are represented respec- tively by the metal plate and the body of the patient. (See
HISTORICAL AND INTRODUCTORY
Fig. 3.— D'Arsonval Auto-Condensation Couch. (Williams.) Fig. 3.) The currents obtained from the various forms of d'Arsonval Solenoid, while of High-Frequency and large amper- age, are of relatively low voltage, and their Therapeutic effects are general rather than local. The wonderfully brilliant Elec- trostatic effects obtained by Tesla with his alternating currents of High-Frequency and High Potential led d'Arsonval and his colleagues to study them therapeutically. Tesla' s original High- frequency apparatus being too large and expensive, a miniature form of his outfit was employed, which was made by Ducretet
Fig. 4.— Miniature Tesla Apparatus. (E. Ducretet.)
HIGH-FREQUENCY CURRENTS
of Paris (See Fig. 4). A current from the Ruhmkorff Coil was connected by the wires (i-i) to the inner and outer coatings of a Leyden Jar; in a discharging circuit, consisting of a coarse wire coil (A-B) in series with a short spark-gap (e),
OUDIN
fl!GHTHD»DJCY (HIGH P0TINT|AL>
Fig. 5. — Diagram of Oudin-D'Arsonval High-Frequency Apparatus, Showing
Intermediate Forms of Current. a, Batteries in "Series." b, Induction Coil, c, Vibrator or Interrupter.
d, Spark-gap. e, Condensers for Leyden Jars. /, D'Arsonval " Solenoid."
g, Oudin "Resonator." h, "Vacuum Electrode.
the oscillations from the condenser induced in a fine wire sec- ondary coil (F), a High-frequency Current of High Potential, which discharged in the form of a flaming arc between the insu- lated terminals at (E). The two coils are concentric and are immersed in a bath of oil for insulation. Another type of appa- ratus used in d'Arsonval's original experiments is indicated diagrammatically in Fig. 5. A Tesld Coil can be used with this outfit consisting of a reel wound with very fine wire contained in a glass tube filled with oil; (See Fig. 6). By
Fig. 6. — Small "Tesla," or "Secondary" Coil, for Use with Primary Solen- oid. (See Fig. 5.)
slipping this tube inside the small Solenoid, the latter is made to act as the primary coil of a High-tension Transformer, the secondary or Tesla Coil being enclosed in a glass tube. A more practical form of this device is known as " d' 'ArsonvaV 's
HISTORICAL AND INTRODUCTORY
9
High-tension Coil," (See Fig. 7), which is in reality a High- frequency Transformer of the Testa-Thomson type, air being used for insulating purposes instead of oil. At the present time these devices are seldom used among European specialists, their High-potential, High-frequency Currents being generally de- rived from what is known as "Oudin's Resonator"; (See Fig. 9).
RKZS
i
Fig. 7. — D' Arson val Bipolar High-tension Coil. (Williams.)
This device consists of a large fiber cylinder or tube, having a number of turns of fine insulated wire wound on a spiral upon its outer surface. The lower end of this wire is connected to the Small Solenoid of oVArsonval. As a rule the latter is incor- porated in the resonator and consists of fifteen or twenty turns of course copper wire wound upon the lower part of the cylinder, as in Fig. 9, the upper end of the solenoid being continuous with the lower end of the Resonator Coil. (See Fig. 8). It is neces- sary that a certain inductive relation exist between the solenoid
10
HIGH-FREQUENCY CURRENTS
and Resonator Coils; they must be attuned, or in resonance. This tuning is usually accomplished by cutting out one or more turns of the Solenoid by means of a movable contact. (Fig. 9). To the upper end of the Resonator Coil is attached a wire which is connected to an insulated metallic electrode, which is
used for applying the "Ef- fluve," or High-frequency Brush Discharge to the body of the patient. This discharge is essentially of a monopolar character and is therefore limited to the treatment of local conditions. To obtain an actual High-frequency, High-potential Current for general as well as local ef- fects, it is necessary to employ a generator of the Tesla- Thomson type. In Europe, however, these effects are usually obtained from a Bi- polar Resonator, two forms of which are shown diagrammat- ically in Figs. 10 and 11. Resonators and Solenoids re- quire a large Ruhmkorff Coil for their successful operation. The current from Static Ma- chines was regarded as of too small amperage for high- frequency purposes. In 1900, however, Dr. H. G. Piffard of New York devised a small apparatus of the Tesla type for obtaining High-frequency effects from a Static Machine. Al- though the current obtained from this apparatus was of small quantity, its potential and frequency were very high, making it especially suitable for the treatment of diseases of the skin. This is known as the "Hyperstatic Transformer," and is quite generally employed in series with the Static Machine in this
Fig. 8. — Diagram of Solenoid and Resonator. (Freund.)
Fig. 9. — Oudin Resonator. (Williams.)
^ALX — 0 o — XJa
B
E
C
Fig. 10. — Bipolar Resonator of O'Farril.
Fig. 11. — Rochefort's Bipolar Resonator. (Guilleminot.)
12
HIGH-FREQUENCY CURRENTS
country. (See Fig. 12). Piffard also demonstrated the possi- bility of obtaining efficient d'Arsonval Currents from powerful Static machines of the modern American type, and devised several instruments for the generation of these Currents.
The study of High-frequency Currents of the Testa-Thom- son type in relation to therapeutics, was undertaken by the author in 1896. During the first few years of his work, he believed himself to be the pioneer in this particular field of inves- tigation, and when he finally learned of the work of d'Arsonval,
Fig. 12.— Piffard's "Hyperstatic Transformer."
he had independently developed a complete system of technic for the clinical application of Electrical Oscillations; had deter- mined the relative value and peculiarity of action of currents of different frequencies, and had founded at the Boston Dispen- sary, through the courtesy of Dr. Frederick Coggeshall, what was undoubtedly the first "High-frequency Clinic" in America. Despite the crudity of his home-made apparatus, the writer satisfactorily demonstrated the undoubted therapeutic value of High-frequency Currents in a great variety of diseased condi- tions, much of the work being done at the above-mentioned Clinic.
HISTORICAL AND INTRODUCTORY 13
A magazine article by Testa, published in 1893, gave the writer his first idea of the nature and therapeutic possibilities of High-frequency Currents. Tesla reported his observations of the stimulating and vitalizing action of these Currents in the cases of several of his assistants, and upon his own organism. Although disclaiming any belief in the therapeutic value of the older forms of electricity then in use (Faradism, Galvanism, etc.), he professed himself as fully convinced of the important part that his High-frequency Currents of High Potential were destined to play in the Healing Art of the future. These facts were not considered at the time, as of more than passing interest, but were brought back to the writer's memory a few years later in a lecture on the X-Ray at the Massachusetts Institute of Technology, in which the methods for the generation of High- frequency Currents were explained, and demonstrated by a small coil of the Thomson type excited by the discharge of a battery of Ley den Jars charged by a Ruhmkorff Coil. There was at this time practically no literature on the subject, except a report of Testa's lecture before the Royal Society of Electrical Engineers, in 1891.
Through the courtesy of Dr. J . B. Sutherland, at that time Professor of Anatomy at Boston University School of Medicine, the writer was given the use of his private laboratory for the purpose of carrying out investigations concerning Roentgen's newly discovered " X-Ray s." His first work was done with a small three-inch spark coil, laboriously wound by hand, and a small Crookes tube obtained from Queen & Co. A few weeks' experience demonstrated the inadequacy of this apparatus for X-Ray work, and the construction of an eight-inch coil was under way when the above lecture was given at the Institute of Technology. This was the real beginning of the writer's inves- tigations of High-frequency Currents, and his first u Tesla Coil" was completed simultaneously with his eight-inch Ruhmkorff. When primary batteries were used as a source of energy he found that the X-Rays from the latter coil were superior to those obtained from "the Testa" and the latter was temporarily dis- carded for X-Ray work.
About this time the writer made the acquaintance of Mr.
14 HIGH-FREQUENCY CURRENTS
T. B. Kinraide and witnessed at his laboratory in Jamaica Plain, a demonstration of X-Rays of such power as to render the bones of the trunk as clearly visible as those of the hand. With- out doubt, Mr. Kinraide was the first investigator to produce rays of such high power, but his methods were so expensive and complicated as to greatly restrict the field of their application. A tremendous amperage was obtained from a large bank of storage cells, the current being interrupted by a heavy Platinum Break of Mr. Kinraide's invention. A Ruhmkorff coil, rated at about eight inches, was thus operated, the secondary terminals being connected with a condenser immersed in kerosene. This in turn was provided with a discharge circuit, consisting of a Tesla-Thomson Coil (immersed in oil), in series with a spark- gap. From the secondary of the High-frequency Coil, Mr. Kinraide derived the currents which he employed to excite his Crookes tube. Some months later he invented his well-known "Kinraide Coil," which superseded his original apparatus. At the suggestion of Mr. Kinraide the writer modified his own outfit, and adapted it for use on the 104 volt, 60 cycle, alternating, Electric Light Current, obtaining results far beyond his expec- tations. The only unsatisfactory feature of this apparatus was the spark-gap, which consisted of two electric light carbons mounted on an insulated support, and separated by a short air space. An air blast spark-gap, as suggested by Prof. Elihu Thomson increased the steadiness and efficiency of the dis- charge, but greatly complicated the apparatus. At this period, the Knott Apparatus Company, of Boston, brought out their "Knott High-frequency and X-Ray Apparatus," which was provided with a simple rotary spark-gap, consisting of a large metal disk, revolving in front of a brass ball. This device, we believe, was the invention of Mr. E. Cate of the Knott Company. The writer's rotary gap, employed in the "Hercules" Coil, is an improved and perfected form of Mr. Cate's device. The Knott Coil, which is described in an ensuing chapter, was the first American High-frequency apparatus placed on the market, and for years was the only successful coil of this kind in use for X-Ray work. With the addition of the Knott spark-gap, the writer's apparatus proved very satisfactory, and was subse-
HISTORICAL AND INTRODUCTORY 15
quently employed by him almost daily in X-Ray and therapeutic work. The marked relief of pain experienced by several rheu- matic patients after undergoing examinations by the X-Ray, revived in the mind of the writer the statements of Testa, regard- ing the therapeutic value of High-frequency Currents, and led to experiments which proved that it was the electricity, and not the X-Ray, which allayed the pain, thus demonstrating the cor- rectness of Testa's theory.
From that time to the present, the writer has studied to per- fect apparatus for the efficient production of Therapeutic High- frequency Currents, the generation of X-Rays being regarded as of secondary importance. From the first, the writer adminis- tered the treatment by connecting the patient to the terminal of his Tesla Coil by means of a metal hand-electrode, the opposite pole being connected with the various devices for causing the discharge to play upon the affected area of the patient's body. A few accidents, in which the electrode was carried too near the body (causing a painful spark) , led to the employment of a tube of glass between the patient and the active electrode. It was but a step to substitute for the glass-covered metal electrode, a Geissler Vacuum Tube, in which the current passes through the body via the glass walls of the tube and the rarefied gas which it contains. This led to the invention of the Vacuum Electrode, a device now universally employed, but which was first devised by the writer in 1897.
In 1898 the writer devised his well-known "Air Gap Con- denser Terminals," shown in Fig. 13, which illustrates the first form of the writer's High-frequency Apparatus that was intro- duced to the Medical Profession. By the use of these termi- nals, in connection with the writer's Bipolar, High-frequency, High-potential Apparatus, a number of entirely new and dis- tinct effects were obtained. In this way, the therapeutic action of Faradic, Pulsatory and Sinusoidal Currents of Low Frequency was added to the general and local effects of the High-frequenc}7 Tesla Currents. Ultimately a number of distinct methods, or "Modalities," were evolved, and in 1903, at the request of a number of physicians who were using the writer's apparatus, he published his results in the form of a small treatise entitled
16
HIGH-FREQUENCY CURRENTS
"A System of Technique for the Therapeutic Use of High- frequency Currents." A chart giving a graphic outline of each of the methods described, was incorporated in the above treatise. (See Fig. 14.) About this time the writer designed his Portable Apparatus and his large "Grand Model" High-frequency Appa- ratus, styled by its manufacturers the ''Hercules Coil." During the past year a simplified, less elaborate form of this apparatus has been placed on the market, being known as the " Ajax Coil." This apparatus has met with the approval of a large number of
Mh hi
Fig. 13. — The Author's Air-gap Condenser Terminals.
physicians, and is in general use in various parts of the country. The writer's latest apparatus is known as the " Hercules Uni- versal," inasmuch as it combines in a single apparatus, the devices of Tesla, oVArsonval and Oudin, and is provided with a large Ruhmkorjf Coil for heavy X-Ray work.
When the X-Ray was first employed therapeutically, in the treatment of cutaneous diseases, the writer made a comparative study of the Static Machine, Ruhmkorff Coil, and his own Tesla Apparatus, and found that the X-Rays obtained from the latter possessed many advantages therapeutically over those generated from the other machines. Since that time he has devised a number of types of Vacuum Electrodes for combined treatment by the Tesla High-frequency Currents and X-Rays, as well as with Ultra Violet Rays, and other types of radiant energy. A complete description of the nature and use of these devices, as
HISTORICAL AND INTRODUCTORY
17
well as the details of a number of types of High-frequency machines of different design and manufacture, will be given in the ensuing chapters.
Fig. 14.
CHAPTER II
ELECTRONS AND VIBRATION
All our conceptions of the external world are derived through impressions conveyed by the nerves corresponding to our five senses. These impressions are the result of vibratory forces which impinge upon the nerve ends. Difference in sensation results from the varying rate of the vibrations and from the character of the medium through which the vibrant waves travel. For example — Sound is the result of mechanically excited waves transmitted through the air or some solid or liquid substance; at about 40,000 vibrations per second sound waves become inaudible, as our auditory keyboard has a limited number of notes.
We explain all natural phenomena by means of two funda- mental conceptions called Matter and Force. Matter, we define as that which occupies space or takes up room. Force or Energy is that which produces a change in the form, nature or position of matter. We assume that all forms of matter are composed of collections of extremely fine particles called Molecules. A mole- cule is the smallest portion of matter that can exist alone. Under ordinary conditions these molecules, or infinitesimal particles of matter do not touch each other, but are separated by rela- tively great spaces. This is due to the fact that molecules possess the inherent property of mutual repulsion, that is, each molecule tends to drive all other molecules as far away from itself as possible. The mutual repulsion of molecules is, how- ever, more or less neutralized by the attraction which each mole- cule possesses for other molecules in its vicinity. These par- ticles of matter are never at rest but are constantly swinging through definite orbits; it is this inherent tendency to orbital motion which causes the molecules to apparently push each other apart.
18
ELECTRONS AND VIBRATION 19
Energy may be divided into Mechanical or Molar force which produces changes in masses of matter; and Molecular force, which acts on the molecules of a mass. Heat is a form of molec- ular force which, when applied to a body, causes its molecules to swing through gradually increasing orbits, increasing the distance between each molecule and its immediate neighbors. This causes the mass of matter to enlarge, and consequently we say that a body "expands" when heated. When molecules are relatively close together, their mutual attraction is very strong, and the mass of matter would appear to us as being very hard and firm. Such a mass is called a solid body. Suppose a solid body were to be heated: the distance between the molecules would increase and their mutual attraction would gradually diminish; after a time a point is reached where this mutual attraction and repulsion just balance each other, and as a result, we have a form of matter in which the particles are so loosely held together that the slightest force is sufficient to break them apart. Matter in this condition is called a liquid. Application of heat to a liquid causes a still further increase in the distances between these molecules with a corresponding decrease in mutual attraction. At a certain point the mutual attraction is less than the repulsion and we have then a form of matter called a gas, in which the particles tend to diverge indefinitely ; consequently the volume of a gas is limited only by the size of the vessel in which it is contained. The above-mentioned property of gases is of great importance, as it has made possible the discovery of the minute entities of which, not only molecules, but their com- ponent atoms are constructed. These particles may be regarded as units of force as well as units of matter. From the latter standpoint they are called Corpuscles ; from the former, Electrons.
The electron is, therefore, the structural unit of all phenomena. It is a minute charge of Negative Electricity, self-centered and integral. There is no good reason for supposing that an abso- lute, solid, material body underlies and supports this negative charge. In a free state, electrons repel each other, yet they are capable of forming alliances, uniting into groups consisting of from 800 to 200,000, each electron of which swings or vibrates through a definite orbit so that a miniature solar system is
20 HIGH-FREQUENCY CURRENTS
formed, the electrons representing the planets, and being held in equilibrium by the attraction of a hypothetical central sun. These wonderful minute systems constitute the atoms of the various chemical elements, the number of electrons in a given group determining its physical and chemical properties and its atomic weight. Thus the Hydrogen atom consists of about S00 electrons and has an atomic weight of 1. Uranium has over 200,000 and an atomic weight of 239. Between these extremes lie the seventy odd groups of electrons which constitute the chemical elements.
In each atom the mutually repellent electrons are held in a state of harmonious orbital motion by a centralizing atmosphere of Positive Electricity in which they are apparently suspended at equilibrium. In the solar system the planets are similarly held by the sphere of solar attraction. Imagine this sphere of attraction to still exist after the removal of the sun and we have a crude idea of the nature of the Positive Electricity which holds the Electrons together in the atom. A simple yet very instruc- tive experiment will demonstrate the universal law of harmoni- ous association, whereby the electrons are formed into atoms.
Several dozen fine steel needles are magnetized from a powerful electro-magnet, so that all the points have a like positive polarity. Each needle is thrust vertically through a small disk of cork and placed in a large, shallow basin of water. The needles are held in an upright position by their floats and the mutual repulsion between the magnetism of the points above the water and that of the "eyes" beneath the water causes the needles to form a circle around the inside rim of the dish. Now, slowly lower over the center of the dish the negative pole of a bar magnet and when the lines of force radiating from it strike the periphery of the dish, the needles will slowly move toward a common center, stopping when the attraction of the overshadowing magnet just balances the mutual repulsion of the polarized floats. In this way, by employing a greater or less number of needles, a variety of beautiful geometrical figures will be formed. The exact number of needles required to produce a certain figure can be determined only by experiment.
With some of these figures the addition of a needle will cause
ELECTRONS AND VIBRATION 21
a dissolution of the regular arrangement, while the withdrawal of one will weaken but not destroy the integrity. Other figures respond in an exactly opposite manner.
Now, these symmetrical groups are analogous to the atoms of the chemical elements, the experiment showing that stable arrangements of the floats recur at regular mathematical inter- vals, just as the atomic weights of the elements indicate the existence of a Periodic Law governing their formation. This Periodic Law was formulated by Mendelejeff some twenty years ago and laid the foundation of modern chemistry. Arranging the elements in an ascending scale, we have some seventy differ- ent forms of substance beginning with Hydrogen, with an atomic weight of 1, and ending with Uranium with an atomic weight of 239. The Uranium atom contains about 200,000 electrons and is the heaviest and most complex atom known to science. So ponderous is it, indeed, -that sooner or later it breaks down spontaneously, forming an atom of Radium (which is less heavy and less stable than Uranium) and one or more simple atoms of the light gas helium. Uranium evidently marks the limit of electronic combination.
"Uranium, Thorium and Radium mark the end, not the beginning of a course of development. They signalize, we can dimly see, the point where the evolutionary design, so far pur- sued with success, ceases to be practicable. As the outcome of its execution we have the whole series of the chemical elements variously constructed of a primal stuff. And that primal stuff consisted, we are driven to believe, in a crowd of 'electrons,' almost infinite in number, incoherent in arrangement, bound- lessly diffusive in space." How were these "electrons" com- bined together to form an atom? It was not possible without the 'application of some force. It involved the doing of loork. Electrons are, no doubt, adapted for agglomeration, yet they will not agglomerate unless under compulsion. Just so much energy as a substance gives out in going to pieces was assuredly expended in putting it together. "A gram of radium, according to Professor Rutherford's indisputable statement, contains a store of power sufficient to raise 500 tons a mile high. An engine of 1,000 horse power would be kept working for three
99
HIGH-FREQUENCY CURRENTS
hours to produce this small quantity of the heaviest of known metals. Whence did this power come? How and why was it directed in this particular channel?" Here we are met by the impenetrable secret of creative agency.
The sketch (Fig. 15) is intended to give a graphic representa- tion of the break down of a Uranium atom. Some of the freed electrons have already re-formed into Helium atoms; the ma-
Fig. 15. — Schematic Diagram Showing Spontaneous Degeneration of Atoms.
I. — Uranium Atom (Ur), breaking down into the Radium Atom (Ra), and the Helium Atoms (He).
II. — Radium Atom (Ra), breaking down into a Simpler Atom (Bi), (which is probably Bismuth or Lead) and the Helium Atoms (He), giving out meanwhile free Electrons (E, E, 5), (Cathode Rays) and Ether Waves of various frequencies; 1 , X-Rays; 2, Ultra-Violet Rays; 3, Light Rays; 4, Heat Rays.
(Redrawn and Revised from a Sketch by Doctor Batten, in the "Archives of the Roentgen Ray.")
jority of the remaining electrons ultimately unite to form a single atom which would appear much larger than the Helium atoms but slightly smaller than the original Uranium atom. Heat rays (4), Ultra violet-light rays (2), X-Rays (1), and streams of free electrons ("Cathode Rays/' 5) are differ- ent varieties of radiant energy given off in the breaking-down process.
ELECTRONS AND VIBRATION 23
Almost all that we know concerning the electron has been learned through the study of the phenomena of Radium and of the electric discharge in Crookes' Vacuum tubes. ("X-Ray tubes.")
We have seen how electrons unite to form the different kinds of matter. Let us now consider them as sources of force. We shall find that the different manifestations of energy are the result of vibrations or perturbations of electrons acting indi- vidually or in collected units. The most subtle and most elusive type of force is that which we call Radiant Energy, and consists of transverse waves propagated in the ether by the orbital or axial rotation of individual electrons, either free or in the atom. Phenomena involving sudden or periodic interference in the motion of electrons through solids, liquids or gases, also give rise to waves of radiant energy. The crack of a whip causes a single pulse or radiating wave in the air which impinges on the ear drum as a sudden, sharp noise; the alternate to-and-fro vibra- tion of a piano string, on the other hand, sends out a series of gradually diminishing waves which blend to form a musical note, of a pitch or frequency equal to that of the vibrating string. Single electrons moving at a high velocity, when suddenly stopped by some solid body, send out isolated "pulses" in the ether; when these pulses follow each other with great rapidity, X-Ray s are generated. It is the extremely short wave length of these impulses which enables them to penetrate solids which are opaque to slower vibrations. X-Rays may be likened to a succession of "whip-cracks" in ether, while light waves are like musical sounds in that they result from the sustained vibration of electrons swinging in their definitely determined orbits. The bright lines of the spectrum are single pitches or "tones," their wave length and frequency being determined by the rate of rotation of the electrons in the different chemical atoms. The relation between the various forms of radiant energy is indicated in the following table, which was arranged by Doctor Batten of London.*
* "Archives," r904, p. 173; Dr. Geo. B. Batten: "The Revelations of Radium."
24
HIGH-FREQUENCY CURRENTS
TABLE OF WAVES OF RADIANT ENERGY
per second.
Rate of travel through the ether:
300,000 kilometers ;
186,000 miles ]
/i=To5o millimeter. MM = millimeter =2J5 inch. CM = centimeter.
M = meter =39£ inches. KM = kilometer =1,000 meters = 1,093 yards.
|
Complete Vibrations |
Oc- taves |
Wave- Lengths |
Observations |
|
Per Second. |
56 |
||
|
55 |
? |
Approximate |
|
|
54 |
? |
Probable position of X-Rays (Roentgen) |
|
|
53 |
|||
|
4,503,599,627,370,496 |
52 51 50 |
0.1/t |
Ultra - violet photographed in vacuo |
|
1,125,899,906,842,624 \ |
/ 0.28/i |
Photo limit of solar spectrum (Cornu) |
|
|
789,000,000,000,000 ( |
) 0.38/i |
Visual limit at violet end of spec- |
|
|
> |
49 |
< |
trum |
|
562,949,953,421.3121 |
] 0.53/x |
Green light |
|
|
451,000,000,000,000 1 |
I 0.76/i |
Visual limit at red end of spec- trum |
|
|
281,474,976,710,656 |
48 47 |
ljU |
Infra-red photographic limit (Ab- ney) |
|
70,368,744,177,664 |
46 45 |
4/1 |
Heat rays of splar spectrum, low- est, measured directly (Langley) |
|
44 |
24/( |
Heating rays observed by bolo- meter |
|
|
43 |
\ |
||
|
42 41 40 39 38 |
J |
Seven octaves unobserved, now |
|
|
V |
partly occupied by probable |
||
|
( |
position of N-Rays (Blondlot), |
||
|
] |
1903 |
||
|
37 |
/ |
||
|
47,000,000,000 |
36 |
2 MM |
Electric oscillations in small spheres |
|
35 |
6 MM |
(Bose) |
|
|
34 |
1.7 CM |
||
|
33 |
2.6 CM |
Electric oscillations in small spheres (Righi) |
|
|
32 |
3.5 CM |
||
|
31 |
|||
|
30 |
|||
|
29 |
|||
|
28 |
ELECTRONS AND VIBRATION
25
|
Complete |
Oc- |
Wave- |
|
|
Vibrations |
taves |
Lengths |
Observations |
|
27 |
|||
|
26 |
446 CM |
Electric oscillations in Hertz reso- |
|
|
o: |
nator, 70 CM diameter |
||
|
10,000,000 |
6iJ 24 |
15 M |
Electric oscillations from 1-pint Leyden jar. |
|
8,388,608 |
23 |
30 M |
Electric oscillations from fly in g- |
|
22 |
bullet photographs (Boys) |
||
|
21 |
|||
|
20 |
|||
|
19 |
|||
|
262,144 |
18 |
1.1 KM |
Electric oscillations, Leyden bat- |
|
17 |
tery circuit (Feddersen) |
||
|
16 |
|||
|
15 |
|||
|
14 |
|||
|
13 |
|||
|
12 |
|||
|
11 |
|||
|
10 |
|||
|
512 |
9 |
585 KM |
Electric oscillations in very large |
|
8 7 |
battery circuit (Lodge) |
||
|
157 |
1,910 KM |
Electric oscillations from conden- |
|
|
6 5 |
ser I microfarad capacity |
||
|
Once per second |
4 3 2 1 |
/ 300,000 KM 186,000 |
|
|
Pendulum beating |
—1 |
\ miles |
|
|
Seconds |
—2 |
||
|
Once in 4.7 seconds |
—3 |
865,000 |
Electric oscillations from storm in |
|
miles |
sun |
||
|
—4 |
In this connection, the following hypothetical experiment is extremely instructive, as illustrating the relationship of vibra- tion to radiant phenomena. It is quoted from a most remarkable little book entitled " Dynamic Thought," by William Walker Atkinson.
"To give one an idea of the differences produced by different rates of vibration, let us imagine a mass of iron, shaped like a great Hop,' capable of being impelled to 'spin' at a constantly
26 HIGH-FREQUENCY CURRENTS
increasing rate of speed, by some mighty will. At first it is seen as a slowly spinning top, manifesting nothing but slow motion, to our senses.
" Now, imagine our top spinning at a rate doubling each second. The first second the top spins at the rate of two revolutions per second. We notice no change, except that we can see the movement. The next second the revolutions are doubled to four per second. Then, doubling each second, we have, respec- tively, revolutions of eight per second, then sixteen, and then in the fifth second, thirty-two per second. Then we begin to notice a change.
"When the revolutions reach thirty- two per second the fric- tion of the moving top on the air causes it to give forth a very low, deep bass note of Sound. This note is like a low, deep 'hum/ and is the lowest possible of perception by the human hearing, although it is possible that some of the lower forms of life may be conscious of still lower vibrations.
"The sixth second the revolutions reach sixty-four, and the low note has grown much higher in the scale. The seventh second records a rate of 128, and the note has correspondingly increased. Then, as the seconds pass, we have successively, 256, 512, 1,024, 2,048, 4,096, 8,192, 16,384, 32,768, the latter, in the fifteenth second representing the highest note recognizable by the human ear, although it is believed that some of the lower animals may recognize sounds too acute for our sense of hearing. During this increase in revolutions from the fifth second to the' fifteenth, the sound-note has risen rapidly in the scale from the low sullen "hum," on through the notes of the musical scale, and beyond the range of instruments, until the shrillness be- comes so intense as to be almost unbearable, and finally terminat- ing in a shrill, piercing shriek like the ' squeak' of the bat, only long drawn out.
"Then from the termination of the sound (by reason of the rate of vibration having become too high) silence reigns for thirty seconds — absolute silence, in spite of the rapidly increasing rate of vibrations; in fact, because of it.
"When the forty-fifth second is reached, and the revolutions have attained the rate of 35,184,372,088,832 per second, our
ELECTRONS AND VIBRATION 27
top begins to emit heat-rays, increasing each second. Then a little later a dull, dim glow may be noticed. Then, as the seconds fly, the dull glow manifests a deep dark-red color, such as one notices in the iron of the blacksmith's shop, soon after it begins to 'glow.' Then, on and on, as the seconds fly, the deep red grows lighter and brighter, gradually changing into orange, then into yellow, then into green, then into blue, then into indigo, then into violet, and then into the color of 'white heat.' Then this 'white heat' changes into a still more dazzling white, and then a white impossible to describe appears, so bright, clear and brilliant that the eye cannot bear the sight. Then suddenly, the intense brightness is succeeded by absolute dark- ness, and the moving top cannot be seen by the eye — and yet it moves on. The highest recorded chemical rays of light are estimated to equal a rate of vibration of 1,875,000,000,000,000 per second. The vibration of the lowest shade of red light is estimated at 450,000,000,000,000, and the highest of violet at 750,000,000,000,000 per second, so we may imagine what the highest line on the spectrum is like.
"Still vibrating, our top, which has become now a mass of vaporized iron, rapidly tends toward still more ethereal forms. It has passed out from the region of light-waves, into another 'Unknown Region' of vibrations, in which region, however, exist the vibrations known to us as the 'X-Rays,' etc. It is throwing off great quantities of electrons. If we were to use a fluorescent screen we would be able to observe the phenomena of the Roentgen Rays, and similar manifestations of radiant energy.
"On and on vibrates the top of what we once called Iron — cold iron, warm iron, hot iron, melted iron, gaseous iron, ethereal- ized iron, if you like. What it is like now, the imagination of man cannot conceive. Still the revolutions continue, doubling each second. What is being produced? The imagination cannot conceive of what this state of Substance, now being reached, is like. By a scientific form of poetry we might think of it as melting into Energy — pure Energy, if there were such a thing. Long since it has been resolved into its original particles — its electrons, and perhaps into the 'stuff' from which these
28 HIGH-FREQUENCY CURRENTS
particles are made. But we must let the curtain drop — the wildest fancy cannot follow the dance of substance any further!"
Many of the most advanced thinkers agree that the electron hypothesis confirms the assertion that Life and Intelligence not only manifest through, but actually constitute all phenomena of the universe. They believe that not only in conscious man do we find the Intelligent Life Principle, not merely in the lower plants, but in the wondrous snow crystals, the particles of the oldest rocks, the molecules and atoms of the so-called "elements" and even in the primitive world-forming unit — the Electron — we discover the fundamental qualities of Living Mind. This principle is exemplified in the electron by its Self-centered Unity, its "likes" and "dislikes," its inherent power of vibratory motion and electrical reaction, and in its ability to ally itself for offense or defense with other similar units, and in their com- pany to evolve to more complex and higher types — to the crystal, to the plant, to the animal, to the man — and beyond! The hard and fast line of demarcation between "Living" and "Dead" matter no longer exists. Up to 1820, chemists divided com- pounds into inorganic and organic, holding that the latter were obtainable only from vegetable or animal material and were formed solely through the mysterious agency of "life," They supposed it impossible to create in the laboratory from inorganic elements an organic compound, such as rose-oil or albumen; just as some present day scientists believe that an impassable barrier exists between the highest chemical crystal and the lowest form of cell life.
Wohler, in 1820, performed the synthesis of urea from ammon- ium cyanate, and proved that it was possible to reproduce in the laboratory all the chemical combinations existing in living structures. Almost any day another "Wohler" may startle the world by apparently "creating" from chemical substances a low form of so-called cell life. Already Professor Loeb and Professor Mathews have come dangerously near this achievement, and they have shown that when this gap is bridged, it will be through the agency of the more subtle forms of electricity.
Similarly, it will be but a question of time and experiment ere the exact electrical nature of normal vital activity will be ascer-
ELECTRONS AND VIBRATION 29
tained. Refinement of apparatus will enable the physician to generate and apply to the diseased organism electrical forces of the exact voltage, wave form and frequency required to restore to the normal the organs and functions deranged by the disease in question.
Electro-therapeutics, which has not even been considered worthy of a place in the curricula of a number of prominent medical colleges, will then become the most important subject in a medical education.
CHAPTER III
ELECTRO-PHYSICS, FROM THE STANDPOINT OF THE ELECTRON
THEORY
From a consideration of the previous chapter it will be readily understood that the advent of the "Electron Theory," while greatly broadening and amplifying our knowledge of the nature and causes of natural phenomena, nevertheless makes it neces- sary for a thorough revision of the laws and definitions which have been generally taught and accepted up to the present time. For example, we have been taught that electricity flows from the positive to the negative pole of a circuit, and that the electric- ity in a Positively charged body exists in a condition of increased pressure or concentration, the reverse being true in the case of a Negatively charged body. Physics has taught us that Electric- ity is an indefinable, elastic "something," equally diffused throughout all matter; and that by removing a portion of the Electricity contained in a given body, and adding it to another body, a Positive charge would be communicated to the latter; while the first mass would be left in a Negative condition. A Positively charged body was analogous to a chamber filled with compressed air; a Negatively charged body, to one filled with rarefied air. These statements have been generally regarded as correct, and have been of no little assistance to the student of electro-physics, but our recently acquired knowledge of the real nature of electricity has demonstrated the incorrectness of the above statements, as well as of many other explanations and theories promulgated in the various books on physics and electricity, which have been published within recent years. The profound, epoch-making character of the discovery and elabora- tion of the "Electron Theory," is not generally realized at the present time, except by investigators and students of pure science. It has been the writer's experience that the members
30
ELECTRO-PHYSICS 31
of the medical profession, including even a majority of the electro-therapeutic specialists, are almost entirely ignorant of the great practical significance, and the wide vista of possibilities which have been opened to us by the discovery of the "Electron Theory." In writing this book, the author has had occasion to consult a vast amount of literature relative to Electro-Thera- peutics; and has been impressed with the confusion and ambi- guity resulting from the attempt to employ the terms and defini- tions of "Nineteenth Century Electro-physics," in conjunction with the revised statements of facts deduced from the "Electron Hypothesis." Within the ensuing year many standard works on physics and chemistry will doubtless be revised and rewritten in the light of our recently acquired knowledge, but as no such textbooks are available at the present time, the writer has deemed it advisable to incorporate in the present volume the main facts of the electron hypothesis; and the elementary principles of electro-physics, as viewed from this modern stand- point.
The first part of this task has been completed in the preceding chapter. The general nature of physical phenomena has been considered and the evolutionary process whereby electrons are united into groups of different sizes and arrangements — forming the atoms of the chemical elements — has been explained in detail. In order to understand the abstruse laws and principles exemplified in the production and application of High-frequency Currents, it is absolutely essential that the student obtain a clear comprehension of the fundamental processes which form the basis of all electrical phenomena, and to this end a brief summary of the simpler facts of electro-physics in the light of recent discovery, will now be given.
Electrical phenomena result, primarily, from the Motion of Electrons, either in a free state, or united into groups, called Atoms. Every atom of every molecule is so constituted that it may be made to give up, or take in one or more Electrons. Atoms of Monad Elements, if basic, or metallic, readily give up a Single Electron, the remainder constituting a Positive Ion. Dyad or Triad atoms give out — respectively, two, and three electrons, when they become Ions. Acid-forming Elements do
32 HIGH-FREQUENCY CURRENTS
not really give up electrons, but each atom attaches to itself an electron and in this manner becomes a Negative Ion. Chemical action results from — or consists in — the union between negative and positive Ions to form Neutral Molecules, called Salts.
An Electron is a Unit charge of Negative Electricity. Neutral atoms consist of one or more thousands of electrons, held in equi- librium in a sphere of positive electricity. There is no such thing as a "positive electron"; that is, an isolated unit of posi- tive electricity, capable of existing in a free condition, as in the case of the negative electron. Positive charges, therefore, are found only in association with atoms, and the Unit of Positive Electricity is an Atom which has temporarily parted with one of its component electrons ; it is, in other words, a Positive Ion.
The various forms of electrical phenomena may be classed under the following heads :
(1) Magnetism. — Which results from the unequal distribution of electrons in a mass of iron or steel.
(2) "Static" Effects. — Or conditions of electrical "charge," which result from the addition, or withdrawal of electrons from a neutral mass of matter. The temporary addition of electrons to such a mass renders it "negatively charged"; the withdrawal of electrons results in a "positive charge." (The attention of the student is called to the fact that these definitions are the exact reverse of those taught before the advent of the "Electron Theory.")
(3) "Dynamic," or "Kinetic" Effects. — Including the various phenomena of "Electrical Currents." These may be divided into : (a) Currents flowing through solid conductors (such as copper wires), in which the electrons are passed along from atom to atom. (b) "Electrolytic" Currents which accompany chemical action in solutions, in which the charges move as "Ions" — the electrons being attached, rather than free as in (a), (c) Electrical discharges in air at ordinary pressures, "Electric Sparks," in other words, which consist of sudden, or momentary surges or discharges, in which both Ions and Electrons are pro- jected across an air space separating two conductors, (d) Electrical currents in gases at extremely low pressures; these con- sist almost wholly of Streams of Free Electrons, moving with
ELECTRO-PHYSICS 33
great speed from the "Cathode" (or negative electrode) to the "Anode" (or positive electrode) of a highly exhausted glass bulb, which is called a "Crookes Tube." The "Streams of Electrons" just mentioned are called "Cathode Rays."
Magnetism *
Magnetism, while usually treated as an electrical phenomenon, has remained a puzzle to physicists up to the present time. The electron theory, which has done so much to dispel the con- fusion in the minds of students regarding the fundamental nature of electricity, has been of great assistance in explaining the phenomena of magnetism, and electro-magnetic induction. In a bar of pure iron, or soft steel, magnetism may be temporarily
Fig. 16. — Magnetism Induced in Iron Bar by Current in Coil of Wire.
induced by the passage of a current of electricity through a spiral coil of wire surrounding it. As has been stated, an electric current involves the passage of electrons through the circuit from the Negative to the Positive pole. In the wire (B' ', Fig. 16) streams of electrons are flowing around and around the soft iron bar (B) , in a gradually ascending spiral path (as indicated by the arrow). Each electron may be regarded as a Moving Magnet attracting electrons in the bar (B), which consequently move through a spiral path, in the superficial layers of the iron, cor- responding to the number of turns in the coil {B') . The streams of electrons rushing around this path, being unable to escape
* Since this chapter was written discoveries have been made which show that the above theory of magnetism is not entirely correct: it should be ac- cepted, therefore, merely as an analogy or aid to the comprehension of the processes of induction. — Author.
34 HIGH-FREQUENCY CURRENTS
from the bar, concentrate in the upper end (N), which in this way becomes the negative pole of a temporary or electro-magnet. The lower end (P), from which a large number of electrons have been withdrawn, would form the corresponding Positive Pole. Now, supposing the current, which is causing the concentration of Electrons in the upper end of the Bar, be suddenly interrupted, the particles in the Iron Bar will endeavor to restore equilibrium and will therefore return to their original positions by the same spiral path which they followed in the course of their upward movement. As every moving electron is a minute magnet these particles in the iron will attract the electrons in the coil of wire, causing them to move around the spiral in a direction opposite to that which they traveled in the form of an electric current, in the first stage of the experiment. In this way a second current would be set up, or "Induced," provided the electrons were free to move in the wire coil; for example, if the two ends of the coil were joined, forming a closed circuit, a temporary current of electricity would flow through this circuit simul- taneously with the return of the electrons in the bar to their original position. If a bar of hard steel be substituted for the soft iron in the above experiment, the electrons will not return after the interruption of the electric current, but will remain fixed; concentrated along spiral lines at the negative pole of the magnet; in other words, the bar will become Permanently Magnetized.
The "Ether" is in some way, intimately associated with the magnetic properties of electrons. When a moving electron is suddenly stopped it acts on the ether as a stone acts upon the surface of a pool of water in which it is dropped, causing "Waves," which radiate in all directions. These waves, when produced by the sudden stoppage of a succession of electrons rapidly moving in a highly exhausted bulb, are of exceedingly short duration and of very "High-frequency" ; they are, in fact, what we know as the "X-Rays," of Roentgen.
Electrons, moving or swinging in regularly defined orbits, produce waves in the ether whose frequency corresponds to the number of electronic rotations in a unit of time. Thus the electrons in the sodium atom, which move around their orbits
ELECTRO-PHYSICS 35
500,000,000,000,000 times per second, give off (when in an in- candescent state, as in the flame of a Bunsen Burner) " Electro- Magnetic Radiations'7 or Waves in the Ether of exactly the same frequency, and a wave length of .65 micron.* Such rays would appear to us as orange-yellow Light, and would, in reality cor- respond to the " Delta" ("D") or "Sodium Line" of the Solar Spectrum.
Other varieties of electronic vibration or rotation give rise to other forms of Ether Waves ; these vary in length and frequency,
Fig. 17. — Diagram Indicating Wave Length and Frequency of Known Forms of Radiant Energy.
a, Mertz Waves, b, Heat Waves, c, Light Waves, d, Ultra Violet Rays. e, Roentgen (X-) Rays.
from the short, rapid "X-Rays" (before mentioned), to the ponderous waves produced by storms in the sun (see Table in Chapter II).
The above, briefly stated, constitutes the "Electro-magnetic Theory of Light," first formulated and mathematically verified by Clerk Maxwell, in 1865 — years before the "Electron Theory" was dreamed of ! In the light of our present knowledge, we may classify practically all natural phenomena as, either the move- ments of electrons themselves, or, as the results of their motion in the form of waves in the ether; that is, as "Radiant Energy."
* The above figures are only roughly approximate.
CHAPTER IV
electro-physics (continued)
The Nature and Generation of Alternating Currents
Imagine a circular tube of metal filled with air or some elastic fluid, and provided at one point of its circuit with a rotary pump, whereby a circulatory motion can be conveyed or im- parted to the fluid in the pipe. (See Fig. 18.) If this pump be set in motion, fluid will be drawn from point (A) and forced toward point (B), the result being a diminished pressure or partial vacuum at (A), and increased pressure at (B), which being transmitted causes a flow of the fluid in the direction of
r.
B
vv — 'J
Fig. 18. — Hydraulic Analogue of "Continuous Current" Circuit.
the arrow, in an attempt to restore the disturbed equilibrium. This results in a continuous current circulating in the tube. Now, supposing, instead of the pump, we imagine the circular pipe to be joined to the extremities of an ordinary engine cylinder with a piston (C) sliding back and forth by the action of the rod (D) (Fig. 19). If the piston be pushed to the position (B'), a temporary flow will be established which will cease when the end of the cylinder has been reached by the piston. With- drawing the piston to (A') causes a temporary current through the tube in the opposite direction. Now, if the piston be
36
ELECTRO-PHYSICS
37
mechanically operated back and forth at regular intervals, a reciprocal or alternating motion is communicated to the fluid in the tube, the motion being graphically represented by the diagram (Fig. 20). Starting with the piston at {A'), as it is
-m
m-
o
Fig. 19. — Hydraulic Analogue of "Alternating Current" Circuit.
forced in, the fluid moves faster and faster, the most rapid motion being at the middle of the stroke, the speed or flow gradually subsiding as the piston comes to rest at (B'). With- drawal of the piston causes a similar flow in the opposite direc- tion, which is represented in the figure by the curve below the horizontal line (the latter, called the "Abscissa," is mathemati- cally divided to indicate time units, such as seconds or minutes; the vertical line, called the "Ordinate," marks the rate of speed
Fig. 20. — "Graphic tracing" of Alternating (Sinusoidal) Current.
of the moving column of fluid). In electricity this method is commonly used to indicate graphically the nature of currents, the divisions of the ordinate being usually made in terms of "Volts" (i.e., in units of electrical pressure, potential, or Electro-
38 HIGH-FREQUENCY CURRENTS
motive force). It is the "voltage" that forces the electricity through the wire or other material which forms its circuit and creates an electrical current. The electricity or moving stream of electrical particles, which is forced through the circuit by the voltage, is measured in terms of the electrical unit of intensity, called the "Ampere."
When water is forced through the pipe (See Fig. 19), it meets with resistance due to the friction of the walls through which it flows. This resistance depends mainly upon the size and nature of the pipe ; similarly, a wire through which a stream of electricity flows offers resistance to its path, and the resistance is propor- tional to the size and length of the wire, provided the latter is composed of the same material throughout.
Different substances offer different degrees of resistance to the passage of electricity per unit of length and thickness. The conductivity of bodies is therefore learned by comparing their respective resistances. The unit of resistance is called the "Ohm" and is represented by a column of mercury one millimeter in diameter and one meter long. A pressure of one Volt main- tained between the extremities of a wire of one Ohm resistance will cause a continuous flow of a current of one Ampere through the wire. Difference of potential ("Voltage") is maintained between the two ends of an electric circuit by (1) Batteries, which transform the energy stored up in the chemicals of the cell into active or Kinetic Electrical Energy; (2) by Generators,. which transform the Mechanical force into an equivalent amount of electrical energy. Under the head of "Generators" may be included (a) dynamos and magneto machines, which operate through Electro-magnetic induction and (b), Static Machines in which the electricity is generated either by friction or by Electro- static Induction.
When the poles of a battery are connected by a conducting wire, a continuous, unidirectional current of electricity will flow as long as the chemical action goes on inside the cell. Such a current would be similar to the continuous flow of fluid around the pipe in Fig. 18. The size or quantity of the stream of energy flowing through the wire (expressed in "Amperes"), depends upon the difference in electrical pressure or potential between
ELECTRO-PHYSICS 39
the positive and negative terminals of the battery and upon the resistance of the circuit. This is an example of "Ohm's Law," which states that the quantity or amperage (C), of a current, is equal to the voltage (E), divided by the resistance (R), expressed in Ohms. Thus when two of the three properties of an electrical circuit are known, we can readily find the third, the formula in each case being as follows:
„ E -p E E=RxC L==R. K=C.
The simplest Generator consists of a coil of insulated wire wound upon a soft iron core and revolving between the poles of a U-shaped or horseshoe magnet. (See Fig. 22.) The tempo- rary magnetism induced in the iron core produces radiating lines of force corresponding to a stress or strain in the surrounding ether, which, when suddenly released, produces, or induces, a momentary current in the coil of wire. In the course of its revolutions between the poles of the magnet, the transient electrical impulses flow through the coil alternately in opposite directions, forming an Alternating Current as represented by the curve (Fig. 20).
The alternating current thus formed is conducted to any desired external circuit by means of two insulated rings, revolving in contact with stationary metallic brushes. All dynamos or magnetos depend upon the above principle but in the Direct- Current Dynamos, a device called a Commutator is employed, which sends all the electrical impulses out in the same direction. In order to obtain a clearer idea of the phenomena of electro- magnetic induction, it may be well to briefly review the theory of the ordinary Ruhmkorff Induction Coil. By introducing a permanent magnet into a coil, the ends of which are connected to a delicate galvanometer, a momentary impulse of electricity is induced, which is indicated by the fluctuation of the needle of the meter, and, when the magnet is withdrawn, a second impulse is indicated, opposite in direction to the first. (See Fig. 21.) The magnet may be allowed to remain in the coil indefinitely without any evidence of current. It is evidently the introduc- tion and withdrawal of the magnet which induces the current in
40
HIGH-FREQUENCY CURRENTS
the coil. In other words, it is not merely the presence of lines of magnetic force, but the act of their formation or destruction which produces the inductive effect in the coil of wire. By successively introducing and withdrawing the magnet from the coil, an alternating current would be generated, the counter-
Fig. 21. — Magnetic-electric Induction. (Williams.)
part of the movement of the water in the tube (Fig. 19) when the piston is in operation. A more efficient manner of producing an alternating current is to rotate the coil of wire so as to present the extremities alternately to the poles of a horseshoe magnet, as described above (Fig. 21). The number of impulses or alterna- tions in a unit of time is called the frequency of an alternating current and depends, in the above generator, on the rapidity with which the coil revolves. An impulse in each direction is called a cycle and is represented thus (^). In technical parlance we indicate the frequency of a current in terms of Cycles per second or Alternations per minute. This is an accepted custom, alternations being always associated with minutes and cycles with seconds (thus a "60-cycle current" is understood to mean a current of sixty cycles per second; we could allude to the same current as one of "7,200 alternations" meaning 7,200 alterna- tions per minute). Currents are said to be of high or low frequency according to the great or small number of cycles or alternations in a unit of time. When a certain fre- quency is reached the currents manifest new and unique proper- ties which differentiate them markedly from low-frequency cur- rents. These peculiar properties are manifested both physically
Fig. 22.— Diagram of Simple "Magneto," Generating an Alter- nating Current.
ELECTRO-PHYSICS 41
and physiologically, the latter being the basis of their therapeutic use. High-frequency Currents were first studied from a physical standpoint by Nicola Testa and Professor Elihu Thomson (see Chapter I). Both Tesla and d'Arsonval first produced these currents by employing alternating generators operated at a high rate of speed and provided with a large number of revolving coils and an equally large number of field magnets. Electro- magnets were employed instead of permanent ones on account of their very much greater power and convenience. Tesla, in this manner, with an alternator having 300 pole pieces, revolving 5,000 times per minute, obtained currents of 10,000 alternations per second (technically a current of "5,000 cycles"). He found that the peculiar properties which become manifest at this frequency, were strikingly emphasized and augmented by raising the current to a very high potential or voltage by means of a "step-up" transformer. In speaking of a High-frequency Cur- rent in the ensuing pages it will be therefore understood that we refer to an Alternating Current of Very High-potential and Very High-frequency (generated usually by the methods of Tesla and Thomson). High-frequency Currents of low potential will be referred to as " d'Arsonval Currents'11 while the unipolar high- frequency high-potential flux, obtained from an "Oudin apparatus" connected to a "d'Arsonval Solenoid," will be denominated as a "Resonator Discharge." The currents employed to-day in High-frequency Therapeutics are of much greater frequencies than those obtained from alternating generators and are pro- duced in quite a different manner. The great number of alterna- tions is obtained by the disruptive discharge of a condenser. A "condenser" (Ley den Jar) is a device which has the property of absorbing or storing up electricity and giving it out suddenly in the form of an electric discharge, when the difference in potential between the positive and negative plates is sufficient to over- come the resistance of the external circuit. Professor Rowland of Johns Hopkins University first employed the condenser dis- charge for the production of High-frequency Currents in 1889. Two years later Tesla described his apparatus in which condenser currents were employed to obtain very high-frequency effects. The practical and economic generation of true High-frequency,
42 HIGH-FRIOQUENCY CURRENTS
High-potential Currents was made possible a few months later by the invention of Professor Elihu Thomson. In Tesla's original coil the step-up transformer, from which the final High- potential Currents were obtained, was very complicated, and consisted of two concentric coils formed of many layers of gutta percha insulated wire wound over a central soft iron core, the whole being insulated with the greatest care, and hermetically sealed in a vessel of boiled-out oil, all air having been exhausted by an air pump. Professor Thomson substituted for this cumbrous device, a transformer without iron core, the ether stresses or lines of force being formed directly by the inductive action of the low-potential High-frequency Currents passing through the primary coil. The latter consisted of a single layer of coarse cotton-covered wire wound on a fiber tube slipped inside of a larger tube upon which was wound a layer of much finer wire, in which the High-potential, High-frequency Current Was induced. A simple bath of kerosene oil was found by Professor Thomson to be fully as satisfactory as the exhausted boiled-out oil of Testa. The final step in the simplification of High-frequency Apparatus was made by the present writer in 1897, who so modified the size and position of the two coils as to allow of their being imbedded in a solid insulating medium of paraffin and rosin. Hundreds of coils made from the writer's formulse are in use throughout the world, and it is almost as rare to hear of such a coil breaking down as in the case of those immersed in a bath of oil.
In order to clearly understand the action of condensers in the production of High-frequency Currents, it will be necessary to study in detail the construction of the Leyden Jar, the nature of its discharge and the conditions which modify this discharge. Whether the latter is a series of elec- trical oscillations of high frequency or a simple unidirectional impulse, depends upon the resistance of the external circuit formed between the plates of the condenser or Leyden Jar (Fig. 23) . If this resistance be considerable, the electricity will cease to flow when equilibrium is established. On the other hand, if the resistance be small, the flow of electricity will not stop at the neutral point, but will act as if the stream of electrons possessed
ELECTRO-PHYSICS
43
material properties and acquired momentum, thereby charging the condenser again in the opposite direction, again discharging
a, Inner Coating.
Fig. 23. — Leyden Jar, or Condenser.
h, Outer Coating, c, Glass Jar. d, Brass Ball Terminal
e, Discharging Wire. /, " Spark-gap."
past the neutral point, and repeating the operation until the electrons gradually come to rest. This operation is analogous to the movement of water in a U tube (See Fig. 24) . Imagine the right hand column depressed, thereby raising the opposite
~
IN
Fig, 24. — A, Water at Rest in "U" Tube. L, Normal Level. B, Displaced Water Oscillating Before Coming to Rest. C, "U" Tube with Arms Joined by Capillary Tube (d) which Prevents Oscillations in Water.
column ; when released the water flows back by gravity, but its momentum carries it past its original position, and it oscillates
44
HIGH-FREQUENCY CURRENTS
back and forth, the height reached by each movement being less than the preceding one, until the water gradually comes to rest. Imagine now that the two arms of the U tube be con- nected by a fine capillary tube, opposing great resistance to the flow of water; in the latter case when the water is depressed and suddenly released, the resistance of the capillary tube opposes the sudden flow of water and prevents its acquiring momentum, and it consequently slowly returns to the neutral level without any oscillatory movement. In an analogous manner the discharge of a condenser is oscillatory so long as the resistance of the external circuit is low, while with high resistance
it becomes a single unidirectional flow, as above stated. Analogy is at fault, however, in one respect; according to the example of the water in the tube, the oscillations will be prolonged to the greatest extent when the walls of the tube possess the least possible resistance, that is, when the tube has the great- est size. In studying a condenser circuit, however, we have to deal with a new form of resistance called Inductance. Inductance acts only upon alternating currents. This inductance results from the flow of the alternating current through a coil; the current reacts upon itself in the convolutions of the coil, and this reaction is called Inductance. With a given coil having a certain number of convolutions wound upon a tube of certain diameter and of given size of wire, there is a certain frequency of alternations to which, instead of opposing resistance, the coil will actually in- crease the duration of the oscillations for each discharge. The frequency of the oscillations of a condenser discharge depends upon its size, technically spoken of as its "capacity"; that is, the amount of electricity which the condenser is capable of storing up at a given voltage or pressure. A definite mathemati- cal relationship exists between the capacity of a condenser and the inductance of the circuit through which it discharges, and
Fig. 25. — Plate Condenser with Inductance Coil and Discharg- ing Circuit.
ELECTRO-PHYSICS 45
in order to obtain High-frequency Currents under the most favorable circumstances, there must be experimentally deter- mined an attunement giving this particular relationship.
To understand this action let us consider the well-known phenomenon of acoustics. A tuning fork when struck emits sound waves of a certain pitch or frequency, which rapidly diminish in amplitude and soon cease entirely. An organ pipe of a different pitch held to the vibrating fork, has little or no effect upon the sound. If, however, the pipe be attuned to the exact pitch or frequency of the fork, the sound waves are greatly increased in volume and duration. This is called the phenome- non of resonance, and the action of the organ pipe on the vibra- tions of the tuning fork is exactly analogous to that of the inductance coil on the discharge of a condenser. When the inductance and capacity of a circuit are exactly balanced or attuned one to the other we have a condition of "electrical resonance," and the coil which re-enforces the oscillations is called the Solenoid of d'Arsonval. (See Chapter I.)
CHAPTER V
PHYSICAL FACTORS INVOLVED IN THE GENERATION OF HIGH- FREQUENCY CURRENTS
Despite the complex and diversified character of the external world, and the countless number of totally different things of which it is composed, we find by analysis and comparison that, fundamentally, Nature's processes are definite, simple and along parallel lines. The apparently abstruse principles underlying the most complex phenomena are often exemplified in the simple occurrences of everyday life. Newton pondered for years on the mystery of Gravitation, but it was the simple fall of an apple that finally led him to formulate its laws. This is an illustration of the "comparative method of study" br "study by analogy" which has been the main factor in the scientific progress of the past century. Until this method was applied to the study of electricity, it was extremely difficult for the student to compre- hend the relation and true meaning of the terms "potential," "intensity" and "resistance," and their corresponding units — the Volt, Ampere and Ohm. At the present time we explain these terms by the study of a stream of water flowing from an elevated reservoir through a pipe connected to a small water- motor. The speed of this motor is proportional to that of the water which flows through it, and depends on the degree of elevation of the reservoir. The higher the reservoir the greater the pressure of the water in the pipe and consequently the greater the speed at which the stream moves. Water flowing from a height of a hundred feet has a "pressure" or "head" of one hundred feet which would determine the velocity or force of the stream. The water encounters "resistance" due to the friction of the walls of the pipe and the inertia of the revolving wheel in the motor. A certain force or head of water flowing through a pipe having a given friction or resistance, would
46
GENERATION OF HIGH-FREQUENCY CURRENTS
47
enable the motor to perform a definite amount of mechanical work; if the resistance of the pipe be doubled by making it either twice as long, or of half its original diameter, the amount of work done by the motor would be just one-half of its previous performance, inasmuch as the amount of water flowing through it in a given time is just one-half of the original amount. Now the laws exemplified in the stream of water are practically the same as those which govern the flow of a continuous current of electricity from a source of supply — such as a dynamo — through
McitQ^ofT-ccsSucc
Resistance /ohm.
ifoU.
Rate of flow.- current i amp.
Work done i JouCe„mte at which work is done I Hate.
Quantity of current in I second, iCoubm,
^*^*W^^««
Fig. 26. — Diagram Showing Analogy Between Falling Water and a Current of Electricity. (Williams.)
a length of wire to an electric motor. The amount of electricity, that is, the number of " Amperes," which flow through the motor in a given time are determined by the pressure or voltage of the current, and the Resistance, or "Ohms" of the wire and motor. A similar comparison has been given in a preceding chapter, but is reviewed here, for the purposes of impressing the student with the value of the method of teaching by "Analogy" or Comparison. (Fig. 26.) The water motor, pipe and reser- voir, in the above example, constitute a "Hydraulic Analogue" in which the water represents the electricity. The work done by the electric motor varies with the pressure and resistance of the circuit just as is the case with the water wheel. The
48
HIGH-FREQUENCY CURRENTS
obvious advantage of this method of study lies in the familiar commonplace character of the Analogue.
The various phenomena which take place in an apparatus generating High-frequency Currents are well exemplified in a
c' ; (c^L-v *-* c "
N9 1
J N<?1'
c
Fig. 27. — Plate I. D'Arsonval Circuit and Hydraulic Analogue.
Hydraulic Analogue, which has been used by Professor Fleming, Dr. Elihu Thomson, and other prominent lecturers. It has been used to explain the action of Therapeutic High-frequency Apparatus by Mr. E. L. Ovington in a chapter on ''High-fre- quency Currents" in Neiswanger's " Manual of Electro-Therapeu-
GENERATION OF HIGH-FREQUENCY CURRENTS 49
tics." In the diagram (Fig. 27) Plate I represents a d'Arsonval circuit side by side with its hydraulic counterpart, while Plate II shows a Tesla circuit with its analogue. Similar letters are used to represent corresponding parts in the circuits and their
Fig. 27. — Plate II. Tesla-Thomson Circuit and Hydraulic Analogue.
analogues. Let us first consider the d'Arsonval method : (a) is a Ruhmkorff Induction Coil, excited by a current from the battery (B) interrupted by the " Break" (/) which induces in the Second- ary coil an alternating current of high potential, which charges the Leyden Jars (d-d), through the wires (b-b), which are bridged
50 HIGH-FREQUENCY CURRENTS
by the sliding rods (c-c), which form the terminals of the spark- gap (G). The outer coatings of the Ley den Jars are connected by the wires (e-e) to the Solenoid (S); two wires (/-/), connect the extremities of the Solenoid respectively to the patient (P), and the metal plate of the "Condenser Couch" (C). A current flows from the Rukmkorff Coil into the jars (d-d), which are thereby charged equally but with opposite polarity; when the pressure in the jars, or rather, when the difference in potential between the jars, reaches a certain point, the resistance of the air-gap (G) is broken down, and the condensers discharge in the form of a Spark. As we know, this spark does not represent a single impulse, but a series of impulses, or oscillations, which diminish successively until the original resistance of the air-gap is established, and the sparks cease to pass. We may assume that by this time a second induced impulse will flow from coil (a) into the jars, and inasmuch as the Ruhmkorff current is of an alternating type, the jars will be charged in a direc- tion: opposite to that which gave rise to the preceding set of oscillations; the spark-gap will then be broken down, and a second set of oscillations will occur. These oscillations neces- sarily traverse the solenoid (S), and are transmitted or com- municated to the external circuit represented by the patient and the plate of the Condenser Couch. To understand exactly how these effects are produced, let us consider their counterparts in the hydraulic analogue. The alternating impulses correspond- ing to those induced in the Ruhmkorff Coil (a) are represented by the alternate reciprocal motions of the piston rods which move up and down in the cylinders (b'-b") causing motion or currents of the fluid in the two chambers (c'-c"), which are separated by the elastic diaphragm (G'). This diaphragm has the peculiar characteristic of "self -repair," or of re-forming after bursting, and may be conceived of as being composed of a thick sticky sub- stance such as the viscid composition, or solution of rubber which is used in filling the so-called "Puncture proof" pneumatic tires. In the "candy pulls" of our childhood days, we may recall the breathless interest with which we watched the progress of the boiling molasses in the exciting moments preceding its removal from the fire ; the viscid surface of the hot mixture was
GENERATION OF HIGH-FREQUENCY CURRENTS 51
convulsed by frequent volcanic eruptions in miniature ; bulging dome-shaped protuberances would form, gradually increasing in size until they became almost hemispherical, finally bursting at the top, discharging a puff of delicious steam, and collapsing,
Fig. 28. — Bursting and Reformation of Elastic Skin on Boiling Molasses.
only to re-form again and repeat the eruptive process. The dia- phragm (G') in the Analogue, bulges out as the pressure of the fluid increases, into a balloon-shaped form as shown in Fig. 28, and finally bursts, after which it is drawn into the aperture again by the cohesion of its own particles, and re-forms itself in the same way, as the viscid bubbles on the boiling molasses. The chambers of fluid (c'-'c"), are prolonged into tubes which are joined at their extremities ie'-e"), by the spiral tube ($')•
The current from the induction coil (A), is prevented from flowing through the solenoid (S), by the insulation of the walls of the glass jars (d-d). Insulating plates, such as glass and rubber, while resisting the passage of a continuous current of
A'
B'
Fig. 29. — A, Pipe Open for Passage of Air. B, Pipe Closed with Elastic Diaphragm, (c). A', Continuous Copper Wire. B', Same Wire Cut at Center and Glass Plate, (c), Interposed Between the Cut Ends.
electricity, readily transmit Alternating Currents of High-fre- quency (i.e., Electrical " Oscillations, " or "Vibrations"). In order to understand this phenomenon, let us consider the two metal pipes A-B in Fig. 29 ; these pipes are exactly similar except
52 HIGH-FREQUENCY CURRENTS
that B is divided into two equal compartments by the elastic diaphragm (C). (A') represents a length of copper wire. (B') represents the same wire interrupted or divided into two parts by the glass plate ((?')• A current of air, such as that used in the pneumatic tubes in department stores would flow readily through an open tube, as (A), but would be absolutely stopped in attempting to flow through (B), by the diaphragm (C). Suppose we speak into one end of (A), the voice will be readily heard at the opposite end ; the tube (B) would conduct the voice in a similar manner, the elastic diaphragm (C) transmitting the vibrations or sound waves, although preventing the actual passage of air between the two compartments of the tube (B). In a similar manner, a continuous current of electricity, which is analogous to the stream of air in the pneumatic tube, while readily passing through the wire {A') is stopped in {B') by the insulating glass plate (C) ; while an alternating current of high frequency, which is analogous to a series of sound waves, readily flows through the entire length of (5'); there is no actual passage of "Electrons" between the two halves of (Br), but the "electrical oscillations" are transmitted by the vibrations of the glass plate (C), just as the sound waves in (B) set up vibrations in the diaphragm (C) which, in its turn, produces similar sound waves in the second half of the tube (B).
If the student will learn to conceive of the High-frequency Currents as Vibrations rather than as actual streams of electrons, he will readily comprehend many of their peculiar and appar- ently paradoxical phenomena. In the analogue, Fig. 27, the rubber diaphragms {d'-d") represent the glass walls of the Leyden Jars (d-d) . Imagine the piston in the left-hand cylinder (&') to be gradually pushed down by means of the lever (L), which causes a corresponding upward movement of the piston in the right-hand cylinder ib") ; the fluid in the left-hand compart- ment (c') will be compressed, causing a bulging of the diaphragm (d') in the direction of the Solenoid or spiral tube (S'), and also distending the friable diaphragm (G') into the form of a spherical bag, projecting into the right-hand compartment (c") ; as the pressure of the fluid in the latter compartment is decreased by the upward movement of the piston (b"), the corresponding
GENERATION OF HIGH-FREQUENCY CURRENTS 53
elastic diaphragm {d"), will be distended in an upward direction as shown in the figure. As the difference in pressure increases, the bulging diaphragm ((?'), reaches a point at which it suddenly ruptures or breaks down, and as it does not immediately re-form, a temporary channel of communication is established between the compartments C'-C", and the water rushes through in the direction of the arrow — its motion being increased by the pres- sure of the distended diaphragms {d'-d"), in their return to a neutral position. By the time this point has been reached, however, the water flowing through {G') from left to right, acquires momentum, which causes it to pass the point of equilib- rium, thereby distending the diaphragms {d'-d") in a direction opposite to that which they occupied in the first instance. The friction of the water against the sides of the compartments pre- vents or retards its flow to some extent, so that the diaphragms {d'-d") are distended to a lesser degree than in the first instance. (See dotted lines.) The water again comes to rest, is again impelled in its original direction by the action of the elastic diaphragms — again passes the neutral point, and in this way oscillates back and forth like a swinging pendulum and finally comes to rest. At this point the diaphragm {G') re-establishes itself in the form of an elastic membrane separating the two compartments, and when the lever (L) causes the piston to again act on the fluid, it again distends into a bag, ruptures and inaugurates a second set of gradually diminishing oscillations of the fluid. By means of the elastic diaphragms {d'-d"), these oscillations are communicated to the fluid in the spiral tube ($'), which, by its added momentum, tends to prolong or increase the duration of each set of oscillations, although lowering or lessening their frequency, or rate of vibration. Two tubes {f'-f"), which are attached at either end of the spiral {S') are united by a chamber divided into two compartments {C'-P') by an elastic diaphragm {K'). Oscillations of the fluid in the spiral {S') will cause cor- responding movements in the compartments {C'-P'), the dia- phragm {K') vibrating in unison with them. The frequency, or number of oscillations of the fluid in a minute or second, depends upon the amount of water displaced or moved from one compart- ment to the other, before the plastic diaphragm (G') bursts or is
54
HIGH-FREQUENCY CURRENTS
ruptured by the unequal pressure transmitted to the fluid by the moving pistons. The number of oscillations in each group— i.e., the number following each breakdown of the diaphragm, depends on the size and length of the oscillatory circuit, or, in other words, upon the amount of friction which the water meets with, in the circuit formed by {c'-c") and ($')• If the spiral ($') is formed of a number of feet of small pipe, the friction which it offers to the water will retard the velocity of the latter and prevent its acquiring momentum ; in consequence of which the
current, or flow, will cease as soon as the diaphragms (d'-d") have returned to their normal, flat condition; in other words, there will be but a single, unidirec- tional flow, or surge of the water for every rupture of the diaphragm ((?'). In studying the production of the High-frequency Current in the d'Arsonval Apparatus (Fig. 27), we may compare
Fig. 30.-Sir Oliver Lodge's Hydraulic the Electricity sent out from
Analogue. the induction coil (a) to the
A, A, Annular Trough Filled with Fluid. _„, „_„^j. „c i.u„ „T^*-„„
B, Flat Steel Spring Fixed at C. D, movement of the water
Metal Ball or Weight Attached to the produced by the strokes of
&' ' the lever (L) ; as the pressure
increases in the jar (d) and is correspondingly lowered in the other jar, the air separating the terminals of the spark-gap breaks down at (G), forming a conducting bridge which temporarily allows the electricity stored up in the two jars to surge back and forth in a series of oscillations exactly similar to those of the water which follow each rupture of the diaphragm (G') in the analogue. If the electrical resistance of the solenoid (S), be considerable, there will be but a single impulse of Electricity instead of a series of oscillations; just as the increase in the resistance of the pipe (S') retards the motion and suppresses the oscillations of the water in the analogue. The increase in the number of turns of wire
GENERATION OF HIGH-FREQUENCY CURRENTS 55
in the solenoid (S), (provided the wire be of large size and low resistance) , prolongs or increases the duration of each set of oscilla- tions, at the same time slightly lowering their frequency, or number per second; the frequency of oscillations is primarily deter- mined by the size, or Capacity of the condensers; the inductance (corresponding to the number of turns in the solenoid), increasing the number, but slightly lowering the frequency of oscillation, as above stated. The rapidity with which the oscillations of each group die out depends upon the resistance of the circuit ; a High Resistance dampening or suppressing all the so-called Secondary Oscillations, leaving only a single Primary Impulse.
Sir Oliver Lodge compares a High-frequency Apparatus to a flat steel spring, fixed at one end in the side of a vessel, its opposite end which bears a metal ball, being free to vibrate in the liquid with which the vessel is filled. (See Fig. 30.) The length and elasticity of the spring represents the capacity of the condenser, and determines the frequency of its vibrations or oscillations. The addition of the metal ball increases the length of time in which the spring remains in a state of vibration, while somewhat diminishing the vibratory frequency. The ball is, in other words, analogous to the inductance of a High-frequency Circuit. The thickness or viscosity of the fluid in which the spring vibrates, represents the resistance of such a circuit; in a light fluid like ether, the spring, if bent back and suddenly released, would vibrate a long time before coming to rest, while a viscid fluid like molasses or tar would cause the vibrations to cease almost immediately.1
The explanations and analogies cited in the preceding pages elucidate the relationship between the essential factors involved in the production of High-frequency Currents ; namely, Capacity, Inductance and Resistance. Mathematically stated, if the Resistance (R), be greater than the square root of four times the
iThe skilled electrician or learned specialist who peruses this book will doubtless criticise the writer for his verbosity and seemingly unnecessary- repetition, but he is reminded that facts, which from his standpoint are of a simple and obvious nature, may be extremely difficult of comprehension for the student who is just commencing the study of electricity, or by the phy- sician desiring to obtain a practical idea of the elements of modern Electro- therapeutics. As this volume is intended both as an elementary textbook for the novice as well as a work of reference for the advanced specialist, the necessity for these few words of explanation will be readily understood.
56 HIGH-FREQUENCY CURRENTS
Inductance (L), divided by the capacity (C), the discharge will be a single unidirectional impulse. Conversely, if the Resistance is less than the above-mentioned quantity, the discharge will be of an oscillatory nature.
If R > -» / - discharge is non-oscillatory
* C
but if R < -v— ^ discharge is oscillatory. » C
With zero resistance the oscillations would continue indefin- itely, but as every circuit must have some resistance, the oscilla- tions following each condenser discharge successively decrease in amplitude and ultimately die out altogether. The ideal condition in a Therapeutic High-frequency Apparatus involves the use of a circuit in which resistance is reduced to a minimum, and the capacity balanced by a suitable inductance. In order to obtain this condition the condenser should be charged by a relatively heavy current at a comparatively low voltage; the Spark-gap must be short, yet must be constructed so as to prevent the formation of an arc between its opposed surfaces. Under such conditions the interval between the termination of one set of oscillations and the beginning of the next, is so small as to be practically negligible, and we consequently have a true " Alternating Current of High-frequency." The writer determined the above facts several years ago, by a series of clinical tests of currents from a number of different types of High-frequency Generators, and has embodied the results in his Improved High- frequency Apparatus which he employs in his practice at the present time. In all apparatus of the d'Arsonval type, using Ruhmkorff Coils, the spark-gap has, of necessity, a very high resistance, varying from one to three inches in length; and it is evident that relatively great intervals exist between succeeding sets of oscillations. This is demonstrated experimentally by the sound at the Spark-gap, which resembles the noise of a "Watchman's rattle," while the condenser discharge of the author's apparatus emits a continuous Musical Note or Tone.
Many physicians believe themselves to be using High-frequency Currents, when in reality they are employing Pulsatory Condenser
GENERATION OF HIGH-FREQUENCY CURRENTS 57
discharges. The "Static Induced," and the "Static Wave Cur- rent," devised by Dr. William James Morton of New York, exemplify the above statement. These currents consist of single short pulses, separated by relatively enormous intervals ; graphi- cally represented, if the distance on the "time-line," or "ab- scissa," corresponding to the rise and fall of a single current impulse be one inch, then, the distance to the next impulse, as represented on the Abscissa, would be seventeen and one-half miles!
CHAPTER VI
EUROPEAN TYPES OF HIGH-FREQUENCY APPARATUS
Before attempting a description of the various types of ap- paratus at present on the market, it will be necessarj^ to briefly review the different methods for the generation of High-fre- quency Currents. Apparatus of the European type, made in
Fig. 31. — Electrolytic Interrupter of Wehnelt. (Williams.)
accordance with the principles of d'Arsonval and Oudin are used with a Ruhmkorff Induction Coil, excited by a Continuous, Uni- directional, Incandescent Light Current. (Fig. 31.) In order to obtain the inductive impulses, an "Interrupter" must be employed ; this may be either electrolytic, or mechanical. If an
58
EUROPEAN TYPES OF HIGH-FREQUENCY APPARATUS 59
Alternating Electric Light Current is to be used, a "Rectifier" or "Valve," may be employed, to cut out the alternations in one direction. (Fig. 32.)
The result is a Pulsatory, Unidirectional Current which may be used with practically the same results as those obtained from the continuous current. If the Ruhmkorff Coil is used solely as
-B^^^/^/N^
"V
Fig. 32. — Nodon Valve, or Rectifier. (Williams.)
a High-frequency Generator, the rectifying valve may be omitted, but if it is also employed for X-Ray purposes, the current must be made unidirectional. In the employment of the High-fre- quency Apparatus of the American, or Tesla-Thomson type, as introduced by the present writer, the conditions are the exact reverse from those above described. Properly speaking the typical Tesla-Thomson apparatus can be operated only on an Alternating Current ; in order to adapt a Direct Current for use in this connection, it must be first transformed into an Alternating
60
HIGH-FREQUENCY CURRENTS
Current. For this purpose a machine known as a " Rotary Converter" is used. A good Rotary Converter will give out about four-fifths of the energy used to excite it, in the form of an Alternating Current of a somewhat lower voltage. No Rukmkorff Coil, or Interrupter is required for the production of the Tesla Currents, both these devices being replaced by an Alternating Current Transformer of the "step-up" type; that is one which takes in electrical energy of a certain voltage, and gives it out at a considerably higher pressure. The " Step-up" Transformer is usually permanently incorporated as a part of
Fig. 33. — Ruhmkorff Induction Coil. (Watson, London.)
the High-frequency Apparatus, whereas the Ruhmkorff Coil is an entirely separate and distinct instrument from the d'Arsonval solenoid and resonator. With this preliminary explanation we may pass at once to a detailed description of the various standard types of High-frequency Apparatus. We will first consider some of the more prominent forms of European apparatus. As most foreign instruments are designed for use with a Ruhmkorff Coil, a short description of the latter device uiSbj not be out of place.
The illustrations (Fig. 33 and Fig. 34) show the appearance and construction of the average European Ruhmkorff Coil. When used for X-Ray or high-frequency work, however, an
EUROPEAN TYPES OF HIGH-FREQUENCY APPARATUS
61
electrolytic or mercury interrupter is usually substituted for the vibrating mechanical break (represented in the figure), which is used only in small portable coils operated by primary or second- ary batteries. The Condenser (E-E-E) which consists of a number of sheets of tin-foil, separated by sheets of mica or waxed paper, is unnecessary when an interrupter of the elec- trolytic type is employed. The function of the condenser is to suppress the "Extra Current" self-induced in the primary coil,
^ -N
Fig. 34. — Ruhmkorff Induction Coil, Shown Diagrammatically. (Williams.)
and this current is an important factor in the operation of the Electrolytic Interrupter. A variety of Ruhmkorff Coils, of differ- ent makes, are in use at the present time, their construction being practically the same except in minor details. For ordinary X-Ray or high-frequency work, coils having a spark-length of from ten to twelve inches are most generally used. It is possible to operate a High-frequency Apparatus of small size on a six- inch Ruhmkorff Coil, but for powerful effects — with the large " Double Resonator," of Dean for example, it would be necessary to employ a coil of from sixteen to twenty inches sparking capacity. Almost all up-to-date mechanical interrupters employ mercury in one form or another. One of the best known is " The Mercury Jet" Interrupter, of Isenthal & Company (See Fig. 35).
62
HIGH-FREQUENCY CURRENTS
The mercury, forced through a small aperture by a pumping device, forms a fine metallic jet, which impinges against the amalgamated surface of a series of triangular blades, attached to a rapidly revolving drum. The height, or level of the mercury jet determines the relative length of the "make," and "break." By means of a rheostat in series with the motor which operates the Interrupter, a range of from one hundred and twenty, to twelve thousand interruptions per minute may be obtained.
Fig. 35. — Mercury Jet Interrupter. (Isenthal & Co.)
Another type of "Mercury Break" is shown in Fig. 36. A vertical plunger is given a reciprocal motion by a Motor which causes it to alternately dip and withdraw from a cup of mercury, the surface of which is covered with oil. While a number of these interrupters are in use, they are regarded as somewhat obsolete at the present time.
Another very popular and efficient instrument is the "Mac- kenzie-Davidson Interrupter (See Fig. 37). It consists of a
EUROPEAN TYPES OF HIGH-FREQUENCY APPARATUS
63
motor, placed in an inclined position ; its shaft terminating in a slate disk, bearing two metal contacts, which dip into a dish of mercury at each half -re volution of the motor shaft. The opera-
Fig. 36. — Dipper Mercury Interrupter.
Fig. 37. — Mackenzie-Davidson Interrupter.
tion of this device is obvious ; it is one of the best of the foreign interrupters.
The conventional European type of "Electrolytic" Break is the well-known interrupter of Wehnelt — a simple form of which
64
HIGH-FREQUENCY CURRENTS
is shown in Fig. 38. In a glass jar of dilute sulphuric acid are immersed a lead plate, or "Cathode," and a fine platinum wire "Anode" which projects for a fraction of an inch into the acid, through a small hole in the lower end of a long porcelain tube. The projecting part of the platinum wire is regulated by a thumbscrew in the cover of the Instrument. The passage of a direct current through this interrupter causes a film of hydrogen gas around the end of the wire, thereby breaking the circuit;
as no condenser is used, the "extra" current — self-induced in the pri- mary of the Ruhmkorjf Coil — discharges in the form of a bright spark, causing a further reces- sion of the acid from the wire point. The acid almost immediately flows back in contact with the anode, and in this way "breaks," and "makes" follow each other in rapid succes- sion. In America this type of interrupter is extensively used, hav- ing been greatly im- proved and simplified during the last two years. In the European types of High- frequency Apparatus, the Ruhmkorff Coil is seldom incor- porated with the resonator and solenoid, the oscillating system being generally sold as a separate apparatus — comprising a pair of Leyden Jars, an adjustable spark-gap, and a solenoid and resonator usually wound upon the same cylinder, the various parts being assembled on a suitable table, or base. The most popular form is shown in Fig. 39, which is known as the "Oudin- Dean Resonator." This model has been extensively copied by manufacturers in all parts of the world. The resonator consists
FiG. 38. — Wehnelt Interrupter. (Williams.)
EUROPEAN TYPES OF HIGH-FREQUENCY APPARATUS
65
of fifty or more turns of insulated copper wire, about three millimeters in diameter, wound spirally upon a wooden cylinder fifty centimeters high, and thirty centimeters ii. diameter. The following- description of the nature of the "Oudin Resona- tor" is quoted from Freund's admirable work on "Radiother- apy."
"As forced resonance is more powerful in its effects than free reso- nance, the resonator was at first attached to one pole of the solenoid of high frequency ; the other pole remained free or was connected to the earth. This arrangement, how- ever, was soon modified. It was found that better effects could be produced by connecting both poles with the resonator. A subsequent modification led to the solenoid of high frequency being sup- pressed and the resonator directly connected with the external armatures of the condensers. The lowest spiral of the reso- nator was then united to one armature, while a spi- ral four to seven turns above it was connected to the other arma- ture by an adjustable clip. The resonator was thus divided into
Fig. 39. — Oudin-Dean Resonator. (Williams.)
66 HIGH-FREQUENCY CURRENTS
two solenoids — a lower and an upper. The lower, or primary sole- noid,"of small size, consisted of a few turns of wire intercepted between the points of attachment of the two cords leading to the external armatures. In it circulated currents of both high and medium frequency, those of high frequency alone being free to pass into the upper solenoid; for the currents of lower fre- quency were close-circuited by it. The secondary or upper solenoid was longer, and was traversed by currents of high frequency alone ; these by reason of self-induction of the circuit, attained an enormous tension. When the three essential magnitudes — capacity, self-induction and resistance — of the two solenoids were by trial proportioned to one another, the upper spirals of the resonator and its terminal were seen bathed in a lively brush discharge like to that produced by a Tesla Coil or influence machine. This effluve is made use of for therapeutic purposes, by connecting the free terminal of the resonator or one of its upper spirals with the wire leading to the electrode."
Although the caliber of the wire which forms the resonator, does not appear to materially interfere with the production of these resonance effects, yet it has, according to Oudin a con- siderable influence on the physical character of the effluve and spark. A fine wire yields a spark, long, thin, sinuous and scarcely painful, with an effluve as poorly nourished; while with a wire of larger dimensions, both effluve and spark gain in force. This depends on the capacity of the wire rather than its self-induction, for every increase in capacity renders the spark more vigorous and painful.
The manner in which connection was established between the poles of the primary solenoid of the resonator and the external armatures of the condensers next attracted attention. It was recognized that the nature of the arrangement that exists for this purpose largely influenced the adjustment of the two sole- noids and the regulation of the effects produced. The crude and unsatisfactory method in which the spring-clip or contact-hook is used to connect the wire from the external armature with the desired spiral soon gave place to others which allowed more perfect regulation and adjustment to be made without in any way interrupting the circuit. Ducretet and Bonnetti invented
EUROPEAN TYPES OF HIGH-FREQUENCY APPARATUS
67
an apparatus in which a grooved contact slip is made to revolve about a fixed resonator, and thus establish contact with the spirals; while Radiguet caused the resonator itself to rotate before the stationary contact point. Both these methods allow of a perfect graduation of effects and an easier adjustment of the solenoids to each other,, without any interruption of contact. The resonators above described, however, are only suitable
J±UL-<) o-X-k
Fig. 40. — Resonator of Lebailly and O'Farril.
Fig. 41. — Rochefort's Bipolar Resonator. (Freund.)
for producing unipolar effects. If double effluvation is to be practiced, the apparatus of Lebailly and O'Farril or that of M. Rochefort must be resorted to. (Fig. 40.)
In the former, the primary solenoid is centrally situated, the external armatures being connected with two intermediate spirals. This creates two secondary solenoids which are situated one on either side of the primary and allows of bipolar applica- tions to be made by connecting the wires leading to the elec- trodes with the free outer terminals of these two solenoids."
Although the apparatus is an improvement on the unipolar
68
HIGH-FREQUENCY CURRENTS
resonator of Oudin, still it is not always easy to equalize the current density at the two poles, and for this reason that of M. Roche fort is preferred.
In the Rochefort model {vide Fig. 41) four Leyden Jars are employed. These are divided into two batteries connected by their internal armatures with the secondary terminal of an induction transformer or spark-coil. The external armatures
Fig. 42. — Upright Solenoid on Cabinet. (Williams.)
are connected with two separate resonators, those of each battery being connected, the one with the lower terminal of one resona- tor, the other with the uppermost spiral of the primary solenoid of the other resonator. When carefully adjusted the density of the current traversing each of the secondary solenoids is equalized; and being of opposite sign, double effluvation can easily be practiced and the effects produced readily controlled. The position of the resonator in the apparatus of different makers calls for a few remarks. In some apparatus, as in Fig.
EUROPEAN TYPES OF HIGH-FREQUENCY APPARATUS
69
42, the solenoid stands upright on the cabinet enclosing the con- densers and spark-gap; in others; as in Fig. 43, it is permanently connected with the condensers; in others again the resonator is horizontally placed so as to allow its inclusion in a cabinet; and lastly, it may be inverted and fixed by its base to the bottom of the baseboard of a High-frequency Table. As there is no special advantage gained by any of these peculiar arrangements beyond the mere matter of saving space, these
70 HIGH-FREQUENCY CURRENTS
eccentricities call only for a passing notice. Much more im- portant, however, is the arrangement for graduation. The crude method of regulation by the contact clip must only be mentioned to be condemned. The regulation by means of a revolving cylinder running on rubbered tires, whose movements can be graduated by the movement of a handle, is the one most to be commended. Not less worthy of mention is the resonator re- volving around a fixed contact in which adjustment is effected by revolving the solenoid by means of the insulating spokes fixed to the disk at its base.
Guilleminot's Spirals. — In resonators formed of wire wound into a helix or solenoid, the energy of the electrostatic field developed by the inducing spirals is only to a very limited extent utilized in the production of induced currents. For the form of the resonator of Oudin does not permit the powerful oscillatory field, created in the vicinity of its spirals, to be employed in generating bipolar currents. Guilleminot has, how- ever, by changing the form of the resonator from a helix to a spiral been able to utilize the energy of the field in producing bipolar effects. The results of his experiments were published in 1901. His resonator is so constructed that the excitation is caused by a single turn, the outer one, which acts as the inducing spiral. (See Fig. 10.)
In practice the adjustment is not made by altering the co- efficient of self-induction of the inducing spiral. This is kept constant and a subsidiary coil of thick wire, with an apparatus for regulating its self-induction, is introduced into the exciting circuit.
The spiral is formed of eighteen turns of wire, 2 mm. thick, held in place by radii of catgut. The smallest circle has a diameter of 33 cm., and the largest a diameter of 83 cm. The interspaces between the successive turns increase in width toward the periphery, since here the difference of potential between successive turns is much greater. The various forms of exciter used in applying High-frequency Currents in medicine are attached to the center of the spiral."
For further details regarding the construction and use of the various forms of spiral resonators the reader is referred to the
EUROPEAN TYPES OF HIGH-FREQUENCY APPARATUS
71
notes on instrumentation compiled by Dr. Clarence A. Wright, and published as an appendix to Freund's "Radiotherapy."
For general treatment with Low-potential, High-frequency Currents of d'Arsonval when especially profound effects are desired, the powerful apparatus shown in Fig. 44 is employed.
Fig. 44. — Gaiffe's Oil Condenser and Heavy Solenoid.
It is manufactured by Gaiffe of Paris from the original designs of d'Arsonval, and consists of a multiple glass plate condenser, immersed in oil, provided with an adjustable spark-gap, and a solenoid consisting of twenty-one turns of copper wire. In the above apparatus we have a departure from the usual European type, in that the condenser consists of alternate plates of glass
72
HIGH-FREQUENCY CURRENTS
and tin-foil, while in other forms of resonators and solenoids, Leyden Jars are employed. There are two other types of European apparatus in which plate condensers are employed — the first shown in Fig. 45, is known as "Gaiffe's Bipolar Resona- tor," and is in reality a form of the Tesla-Thomson apparatus. The solenoid is not connected with the resonator, the currents in the latter being induced by the rapidly alternating Electrostatic Field surrounding the solenoid. Discharges of High-frequency and High-potential may be obtained from either terminal of the
Fig. 45. — Gaiffe's Bipolar Resonator.
resonator, while true High-frequency Currents are produced when the patient is connected with both terminals. This ap- paratus is usually operated from a Ruhmkorff Coil excited by a "Direct" incandescent light current. Alternating currents which are extensively used in America and which are peculiarly adapted for exciting High-frequency Apparatus of the Tesla- Thomson type, have only recently been introduced into the different European cities. There is every indication, however, that currents of the alternating type will entirely supersede the " Direct" continuous current within a few years. Recognizing this fact, Messrs. Gaiffe of Paris have recently introduced an
EUROPEAN TYPES OF HIGH-FREQUENCY APPARATUS
73
extremely efficient High-frequency and X-Ray Apparatus, designed for use on the alternating current, without the necessity for interrupting or rectifying the latter. As this instrument is being very generally employed by European specialists, and as it also illustrates the differences in construction and operation between European and American High-frequency Apparatus of the u closed-circuit transformer" type, it has been deemed advisable by the author to quote the following detailed descrip- tion from Belot's work on "Radiotherapy":
"This new apparatus makes it possible to utilize an ordinary alternating current, without an interrupter, either for the pro- duction of X-Rays or for High-frequency Currents. Hitherto, if we wished to employ an alternating current, we had to use a Ruhmkorff Coil — i.e., a transformer with an open magnetic circuit, supplied with a special form of interrupter. The choice of this lay between an electrolytic interrupter and a self-regulat- ing interrupter of Villard, and it is well-known how difficult it is to regulate either of these instruments.
"It is true that a few years ago a transformer with closed magnetic circuit was made, and that this was used without an interrupter; but, though theoretically perfect, this apparatus rapidly deteriorated with use. M. Villard was the first to adopt this arrangement. The rapid breakdown of the end coils of the secondary was due to the reflected Hertzian waves.
"To guard against these acci- dents we were obliged, even when working with High-fre- quency Currents, to employ comparatively low tensions of 15,000 to 20,000 volts. The results obtained were not satis- factory, and even then the transformers broke down. With X-Rays, where a higher tension was required, the appa-
Fig. 46. — Condenser. (From Belot.)
74
HIGH-FREQUENCY CURRENTS
—Liquid Resist- (From Belot.)
ratus soon became useless. The trans- formers were soon abandoned, and the ordinary coils continued to be used. These are subject to the same dangers, but on account of their smaller output, they de- teriorate more slowly. Thus one of their greatest imperfections has added to their longevity.
"The irregularities of the interrupter, of whatever form, render impossible even an approximate estimate of the output of the secondary. The great novelty in Gaijfe's apparatus is a pro- tective arrangement, which has already been presented to the Academie des Sciences by d'Arsonval. This absolutely prevents the breakdown of the instrument by arresting the reflected Hertzian waves. It is composed of various condensers and resistances.
"Their arrangement and magnitude are determined by con- siderations of the insulation of the coils of the primary, and the nature of the High-frequency Waves which are required.
"These improvements have been so successful that the instal- lation can be employed for all forms of practical work — the condensing couch, the em* uve, resonance, bipolar radiations or X-Rays.
"The apparatus consists of an ordinary transformer, with closed magnetic circuit, receiving an alternating current of 110 volts, which it converts into one of 60,000 volts.
"The protective arrangement is threefold. Firstly, there is a series of condensers arranged between the poles of the secondary (Con., Fig. 46). Secondly, liquid resistances are introduced into the circuit, on either side of the transformer (Resist., Fig. 47). Finally, other condensers are introduced, between the liquid resistances and the tube (C, Fig. 48). These latter are the d'Arsonval High-frequency Condensers.
"They have the further advantage of insulating the operator, and thus prevent any danger from his accidentally touching one of the poles. At the same time they are a convenient method of limiting the current which passes through the tube.
EUROPEAN TYPES OP HIGH-FREQUENCY APPARATUS 75
" The whole apparatus is enclosed in a glass-fronted cabinet, which obviates all danger of accident. The top is surmounted by a marble slab, to which are affixed the voltmeter and ampere- meter, for measuring the primary current, a rheostat resistance interposed in the primary current, and the terminals for the high-tension current.
"The parts are so arranged that the apparatus may be used at will for high frequency or X-Rays by simply removing the Villard valves and interposing a spark-gap in their place.
Fig. 48. — Arrangement of Valves, Tube and Meter. (From Belot.)
" This apparatus is free from danger and easily adjusted. The current may be regulated by merely moving the handle of the rheostat. It will give much greater power than any which can possibly be required at the present time. When the apparatus of distribution has been perfected, and more power is required it will only be necessary to increase the capacity of the con- densers, which act as taps to regulate the output. The ap- paratus is, moreover, always ready for use; there is no trembler to get out of order, no mercury or petroleum to require constant
76
HIGH-FREQUENCY CURRENTS
renewal, and no noise to disturb the patient and wear out the nerves of the operator.
" Let us now inquire how it is adjusted for producing X-Rays. The current should pass in one direction only. As the alternating current produced by this transformer changes its polarity with each oscillation, one series of waves must be absorbed before reaching the tube. For this purpose two Villard valves
Fig. 49. — Transformer. (From Belot.)
(P-Pr Fig. 54) are inserted in parallel with the tube in the manner indicated by Villard himself.
" The discharge through the Roentgen Tube is perfectly regular, the fluorescent screen being as steadily illuminated as when a static machine is in use. The means for complete adjustment is afforded by the rheostat in the primary circuit.
"There is theoretically no limit to the power which can be obtained by the use of this apparatus. As soon as the con- struction of the tubes have been sufficiently improved, with a view to increasing the intensity of the rays, the length of 'ex- posure in radiography and the time of application in radio-
EUROPEAN TYPES OF HIGH-FREQUENCY APPARATUS 77
therapy will be greatly decreased. At present the intensity of the X-Rays obtainable is limited by the fear of injuring the tubes.
"This installation may be arranged to obtain stereoscopic radiographs. Two Roentgen Tubes may be illuminated at the same time by using one of the two series of waves for each tube.
Tromfft
73
HI- \
\ \
V -JH--,
HlSISTMCe . ugmo ;
; icsmuu
'. UtVIO
\Y
h
\Y 4-
i> A XV w»
VTlLlStTIOtl
Fig. 50. — General Diagram. (From Belot.)
"An automatic shutter, whose movement synchronizes with the interruptions of the current, is required. Such a shutter has been invented by Villard.
"This apparatus may be also used with a continuous current. A commutator converts the continuous into an alternating current. By this means we get rid of the interrupter and the Ruhmkorff coil, both of them very imperfect and unsatisfactory
78 HIGH-FREQUENCY CURRENTS
instruments. The utilization of instruments for measurement is thus greatly facilitated. It may be objected to this form of
Fig. 51.— Top Shelf of Cabinet. (From Belot.)
installation that, since it is supplied by the alternating current, it will be influenced by any variation in the mains. The only possible variations, however, are changes of potential and changes in the rate of alternation.
Fig. 52.— Lower Shelf of Cabinet. (From Belot.)
" Neither of these ever varies by more than one per cent., and their effect is therefore negligible. This is quite otherwise if
EUROPEAN TYPES OF HIGH-FREQUENCY APPARATUS 79
ordinary current converters are used. These depend for their effect on synchronism with the current, and are therefore much more sensible to brief variations in the main.
"This installation is equally adapted for high-frequency work.
SPIN7ERHC TRE W'
Fig. 53. — Springs and Contact Plate. (From Belot.)
It is only necessary to remove the Villard valves and insert the spark-gap in order to adjust it for this purpose.
"As we have already stated the whole of the apparatus — transformer, regulators, condensers and spark-gap — is arranged in a cabinet. Within the cabinet are the coils of the trans- former, as shown in Fig. 49. These should never be used outside the case*
* Radiotherapy, by Dr. J. Belot (Rebman Company, New York) .
80
HIGH-FREQUENCY CURRENTS
Volimetre
^—mmmh
r^MMJLWMWULn
Con.
Hh
" In Fig. 50, we give a general diagram of the installation, and Figs. 51 and 52 show the arrangement of the two shelves of the cabinet, with the connection of the transformer, condensers, resistances, etc.
" Fig. 53 also shows the springs, X-X' , and the contact plate. The latter is attached to the door, and thus breaks the circuit s whenever it is opened. All danger
from electric shocks is thus obvi- ated, since the apparatus cannot work unless the door is shut. All ~~\l_J | ifffearfrt dangerous apparatus is thus out of
the way of the operator.
" The safety-fuses, measuring in- struments, and regulating appara- tus are attached to a marble slab on the top of the cabinet, as shown in Fig. 54.
" This new installation of Messrs. Gaiffe seems to meet all theoretical requirements. We have had many opportunities of proving both its safety and its adaptability to prac- tical conditions."
In addition to those already described, a large variety of High- frequency Apparatus of the Oudin- d'Arsonval type has been placed on the market by the European manu-
FiG. 54.-Regulating Apparatus, facturers. Of these may be men- Arrangement of Transformer, tioned the outfit shown in Fig. 55,
made by Max Kohl of. Chemnitz, in which the Ruhmkorff Coil is conveniently located in the lower part of a handsome cabinet, the two upper compart- ments being occupied, respectively, by the coil terminals, interrupter and meters, and by the High-frequency Appara- tus proper; the latter being a small solenoid, separate from the resonator, to which it is connected by means of a spring clip and flexible wire. This outfit is the most frequently em-
» Resist
Resist*
P P
Tube * -i r
EUROPEAN TYPES OF HIGH-FREQUENCY APPARATUS 81
ployed form among the German specialists, while the upright type of resonator, as shown in Fig. 56, is preferred in England and France. As has been previously stated, the development of High-
FiG. 55. — Isenthal's Complete High-frequency Apparatus. (Williams.)
82
HIGH-FREQUENCY CURRENTS
frequency Therapeutics in America, began with the work of the present writer in 1896. During the first four years of his investi- gations, which were carried on upon entirely different lines from those followed by d'Arsonval and his. colleagues, he com- pleted the designs for the first practical Therapeutic High- frequency Apparatus introduced to the American profession. It had been used for several years in his private practice, before the widespread interest in its remarkable therapeutic effects
E~ ItltPW"
Fig. 56. — Resonator and Condensers (small model). (Williams.)
led to its being placed upon the market. The first few machines were made from the writer's designs, and under his personal supervision, by Mr. E. L. Ovington of the Massachusetts Institute of Technology.
The apparatus was subsequently manufactured by Mr. Ovington who devised several valuable improvements which increased its efficiency and lessened its liability to breakdown. It was at this time known as the " Strong-Ovington Static Induc- tion and High-frequency Apparatus." (See Fig. 57.) The only High-frequency Apparatus on the market at the time the
EUROPEAN TYPES OF HIGH-FREQUENCY APPARATUS
83
author's machine made its appearance, was the "Knott Coil," mentioned in a previous chapter (see Fig. 58). This apparatus, however, was used solely for X-Ray purposes, the therapeutic possibilities of the Testa currents and the technic for their application being unknown to the profession until after the appearance of the writer's apparatus.
The "Knott Apparatus" in common with all other High- frequency Coils made prior to 1899, was assembled in oil; and the impossibility of preventing the latter from oozing through the joints of the heavy oak box in which it was contained, was
Rofery
Spark -$&p.
Fig. 57. — Diagram of the Author's Original Type of High-frequency Appa- ratus; "The Strong-Ovington Coil."
one of the chief disadvantages of the apparatus. Both Testa and Thomson had stated that a liquid insulating medium was absolutely essential for High-frequency Apparatus, and that any solid substance, such as wax, or rubber, would sooner or later break down and allow the currents to pass.
The great power and volume of Testa High-frequency Currents and the simple character of the generating apparatus, attracted the attention of certain European investigators shortly after the early clinical results of d'Arsonval and Oudin were published. Clinical tests were therefore made of currents generated on the Testa-Thomson principle, but their obviously great therapeutic
84
HIGH-FREQUENCY CURRENTS
power was offset by several serious and apparently insurmount- able defects. The attitude of the European profession toward the Testa currents is well expressed in the following quotation from an article which appeared several years ago in a promi- nent English journal:
"High-frequency Therapeutics as practised in Europe, is unknown in America, except for a few isolated attempts to apply Tesla currents for the relief of disease. These currents were thoroughly tested several years ago by European investiga- tors, who found them to be absolutely impractical for therapeutic
9
X
8
I4K=^
t--<vr«f-.«^f — ■
Transformer
"*3
rjT :TT! ! i i
Ui ' • i i i i i i Condenser-
1 • ' I ' ! ! ! ! ! 1 i i ' ! ! i ! .
L'_l_U_LJ.J.i.J.i
7
Fig. 58.—" The Knott" High-frequency Coil, Working Part Immersed in Oil.
purposes. The chief objection to the use of Tesla apparatus in therapeutics are:
"First — The great expense and cumbrousness of the apparatus, the parts of which must be permanently immersed in a bath of oil.
"Second — The great volume and power of the currents and the impossibility of properly regulating or controlling them.
"Third — The great danger attending the use of closed-circuit transformers in connection with alternating currents.
"The last objection is by far the most serious, the investigators having narrowly escaped a fatal shock while experimenting with currents derived from a Tesla apparatus."
EUROPEAN TYPES OF HIGH-FREQUENCY APPARATUS
85
The above quotation has been widely circulated during the last few years by manufacturers of High-frequency Apparatus of the Oudin-d1 Arsonval type, in the attempt to prejudice the profession against Tesla apparatus for therapeutic purposes. It will be noticed that the above objections do not apply to the currents, but to the apparatus which is employed in producing them. For a number of reasons, which will be discussed in a future chapter, the therapeutic action of currents of the Tesla type is superior to, and more efficient than that of the d' Arsonval
Fig. 59. — Diagram of the Author's Apparatus, Adapted for the Generation of heavy D'Arsonval Currents, as Avell as those of the High-potential ("Tesla") type.
a, Alternating Generator, b, Step-up Transformer, c, Condenser, d, Spark- gap, e, Switch for Discharging the Condenser through the D'Arsonval Solenoid (g); or the Tesla Coil (/). h, Sponge-covered Electrodes.
Current or of the Resonator Discharge. The writer demonstrated this fact, at least to his own satisfaction, in 1901, at which time he made a comparative study of the American and European types of High-frequency Currents. D'Arsonval Currents of even greater amperage than those obtained from a solenoid and Ruhmkorff Coil, were readily obtainable from the writer's early form of High-frequency Machine by the simple addition of two binding posts, connected to the extremities of the primary coil of the " High-frequency " or " Tesla Transformer." (See Fig. 59.) The writer discarded oil as an insulator during the first year of his investigations. By a suitable method of construction he
86 HIGH-FREQUENCY CURRENTS
arranged the primary and secondary coils of his "Testa Trans- former," so as to isolate the points of highest potential, thereby lessening the tendency of the High-frequency Current to jump from the secondary to the primary coil. In this way he made •possible the use of wax or paraffin instead of oil. This not only removed the objectionable features of the latter, but greatly increased the strength and durability of the apparatus, it being almost impossible to injure a Tesla Coil by any mechanical means, after the solidification of the wax in which it is imbed- ded. The same insulating medium was employed by the writer in the, construction of his condensers, and although he has from first to last, built up his condensers with glass plates, coated with tin-foil, he has had but very little trouble from short circuiting or breaking down of the Dialectric. The substitution of wax for oil not only greatly simplified the apparatus but ap- preciably diminished the expense of its construction.
Scarcely a week passes that the writer's attention is not called either verbally or by letter to the "great danger" attending the use of Tesla High-frequency Apparatus. "Aren't you afraid of getting killed?" and "Isn't it very dangerous to use a 'closed- circuit transformer/ such as the one employed in your ap- paratus?" In reply to these and similar queries the following answers are usually given: "I have experimented with closed- circuit transformers, such as are used in my High-frequency Apparatus, for nearly ten years, during which time hundreds of shocks have been accidentally received both by my assistants and myself, yet in no case has there been any injurious or danger- ous result, the reason for this being the peculiar construction of my step-up transformer and the relatively low potential of the secondary currents obtained from them."
In an ensuing chapter the effect of the degree to which the voltage is raised in the step-up transformer, on the resulting High-frequency Current, will be exemplified by comparing a series of coils, of different design, in which the potential obtained from the initial transformation ranges from 1,000 to 60,000 volts. For the present, it is sufficient to state that as a result of years of experiment, the writer has found that an alternating current of from five to twelve thousand volts is the most efficient for
EUROPEAN TYPES OF HIGH-FREQUENCY APPARATUS 87
charging the condensers of a therapeutic Testa apparatus. The transformer from which this current is obtained is not only pro- tected by a graduated inductive resistance coil, but is so con- structed as to automatically limit the amount of current which it draws from the incandescent lighting mains. When the European investigators construct apparatus on the Tesla prin- ciple, they are apparently influenced by their knowledge of d'Arsonval's methods, which involve the use of Rukmkorff Coil currents of from 50,000 to 100,000 volts. It is probably this fact that has led them to employ the 60,000 volt transformer in the new X-Ray and High-frequency Apparatus recently intro- duced by Messrs. Gaiffe for use on alternating incandescent light circuits (See Figs. 47-54). It is obvious that an alternating current of low frequency, and such a relatively high voltage, would produce dangerous and probably fatal results if accident- ally passed through the human body. It will be seen from the preceding paragraphs, that the objections to the use of Tesla coils, cited by certain European authorities, do not apply to the apparatus employed by the writer in the elaboration of his "American System of High-frequency Therapeutics."
CHAPTER VII
THE DEVELOPMENT OF AMERICAN HIGH-FREQUENCY THERAPEUTICS
Earlier Forms of Alternating Current Apparatus
As has been stated, the first High-frequency Coils manufactured in America were of the Tesla-Thomson type. The "Knott Coil/' which has been already described, was placed upon the market in 1897, and was used almost exclusively for the pro- duction of X-Rays. The " Strong-Ovington Apparatus," which
Fig. 60. — Kinraide Coil; Alternating Type.
was the American pioneer in Therapeutic High-frequency Coils, made its appearance in 1902, although the machine from which it was designed had been in constant use in the writer's practice since 1896. In 1901 the "Kinraide X-Ray Coil" was placed upon the market, and on account of its simplicity and relatively low cost met with an extensive sale. The publication of the writer's clinical results created a wave of interest in High-fre- quency Therapeutics, and led the manufacturers of the Kinraide Coil to exploit it for therapeutic purposes. (Fig. 60.) Many phy- sicians possessing instruments of this type began to employ them in their practice in accordance with the technic described by the writer in several short articles which were published in the
AMERICAN HIGH-FREQUENCY THERAPEUTICS
89
medical journals of that period. The results were as a rule dis- appointing, and led in some cases to questions as to the relia- bility of the writer's statements regarding the therapeutic value of High-frequency Currents. In order to understand the reason for the disparity between the results obtained by the users of Kinraide Coils, and those produced by the writer's currents, the details of construction and the peculiarities of action of Mr. Kinraide' 's ingenious invention, may be briefly considered. His coils are of two types, designed respectively for the Direct, and for the Alternating Current. In the latter type, an Alternating
Fig. 61. — Diagram of Kinraide Coil Showing Relation of Spirals.
Current of 104 volts — (its frequency being generally 60 cycles per second) — passes through a small closed circuit transformer which "steps it up" to a pressure of about 1,000 volts; the latter circuit is then employed to charge a condenser, consisting of a large number of sheets of tin foil separated by thin sheets of flexible or "built up" mica. This condenser discharges dis- ruptively across a short spark-gap between heavy copper plates, in series with the primary circuits of two High-frequency Coils, the latter being the unique features of the Kinraide apparatus. (Fig. 61.)
Each primary High-frequency Coil consists of six turns of thin copper ribbon wound one upon the other like the outer layers
90
HIGH-FREQUENCY CURRENTS
of a roll of tape; a strip of varnished paper serves as insulation. Each primary coil when completed forms a ring or hoop, about eight inches in diameter and one inch in width, which fits tightly over a hard-rubber cylinder containing the secondary coil, the latter being concentric with, and in the same plane as the pri- mary coil. The secondary coil consists of a moderately fine wire wound in the form of a concentric flat spiral, and insulated with the greatest care. This ingenious construction renders a breakdown practically impossible inasmuch as the point of the highest potential is at the center of the spiral, while the outer turns are rendered practically neutral by the use of two High- frequency Coils, connected in series and wound oppositely or sym- metrically, the outer ends of both the primaries and secondaries
100V.6CU
Fig. 62. — Tesla-Thomson High-frequency Apparatus.
a, Alternating Current Generator, b, "Step-up" Transformer, c, Conden- ser, d, Spark-gap. e, Tesla-Thomson High-frequency Transformer.
being connected by a single wire ; the device is still further safe- guarded by connecting the middle point of the wire which bridges the primary and secondary coils, to a single binding post attached to a ground connection.
Every Tesla-Thomson High-frequency Apparatus theoretically consists of three transforming devices arranged in an ascending series. (Fig. 62.) The first is an ordinary " step-up " transformer, having a closed magnetic circuit or "core" of soft iron, differing only from the commercial transformer used on alternating incandescent light circuits, in that it raises, rather than reduces, the potential of the alternating current. It is sometimes called the "High-tension Transformer," and while increasing the voltage, produces no effect on the frequency of the current. The second essential factor in a Tesla-Thomson apparatus converts the Low-frequency High-tension Current into a High-frequency
AMERICAN HIGH-FREQUENCY THERAPEUTICS 91
Current; it is essentially a frequency transformer, and has no effect on the voltage, or potential of the current. It consists of a condenser and a discharging circuit containing a certain amount of inductance in series with a spark-gap; this inductance forms the primary circuit of the "Tesla Coil/' in which for the second time, the voltage of the current is increased. This coil possesses no iron core, and raises the current to an extremely high poten- tial; the ratio of the voltage of the primary, to that of the sec- ondary circuit, depends on the number of turns in the primary coil as compared with the number of turns in the secondary. This law of transformation applies also to Ruhmkorff Coils, and to ordinary closed-circuit transformers, and may be used to calculate the approximate voltage and. amperage of their differ- ent circuits: it is mathematically stated as follows: —
, VP:VS::TP:TS and AP:AS::TS:TP
in which P, and S, stand respectively for the Primary, and Secondary Circuits; T for the number of turns of wire; A, for the amperage, and V, for the voltage. It is evident from the above equation that the voltage in the coils of a transformer varies directly, while the amperage varies inversely, with the number of turns of wire. The frequency of the current from a Tesla coil, is an inverse function of the capacity of the condenser; the greater the capacity, the lower the frequency, and vice- versa.
In consideration of this fact it will be evident that the fre- quency of the Kinraide coil is extremely low, — too low, in fact, to produce the characteristic physiological effects to which the High-frequency Current owes its great value as a therapeutic agent.
In the early years of the writer's investigations he made a series of comparative tests in order to determine the relative therapeutic values of High-frequency Currents of different rates of oscillation. A variety of apparatus was employed, the lowest frequencies being derived from the Kinraide Coil and the highest, from a small Tesla Coil, excited by a current from a pair of me- dium-sized Leyden Jars connected to the terminals of a ten-
92
HIGH-FREQUENCY CURRENTS
plate Waite & Bartlett Static Machine. The currents from the apparatus just described, while necessarily of extremely small amperage, were of extremely high voltage and frequency ; char- acteristics which rendered them of especial value in the treat- ment of diseases of a superficial and circumscribed nature. The writer's practice at this time was confined almost exclusively to the treatment of diseases of a nervous and rheumatic character, and the " Static High-frequency Apparatus" was seldom used after the completion of the series of comparative tests above
Fig. 63. — Piffard's Hyperstatic Transformer.
described. A year or two later a perfected form of Static High- frequency Apparatus was devised by Dr. H. G. PiJJard, of New York City. This device which is known as the "Piffard Hyper- static Transformer,'7 has given excellent results, and is widely employed by users of the static machine. (Fig. 63.) Piffard has achieved remarkable results with his little apparatus, especially in dermatological work ; he has recently improved and modified its construction so as to adapt it for use in connection with a Rukmkorff Coil. It forms an integral part of an American High- frequency and X-Ray Apparatus which has recently been placed upon the market and which will be described in an ensuing- chapter.
AMERICAN HIGH-FREQUENCY THERAPEUTICS 93
It is obvious that oscillating currents of different frequencies affect the functions of the body in different degrees — an as- sumption which is confirmed by clinical experiences — the "Hy- perstatic Currents," — which are higher than the majority of Therapeutic High-frequency Currents, — while valuable in the treatment of skin diseases, are less efficient in the treatment of constitutional ailments involving depleted nervous energy and poor circulation, while the currents from the writer's apparatus are especially adapted to the treatment of the latter conditions.
Diseases involving the muscles and motor nerves are most effi- ciently treated by currents of a very low-frequency — that is, Low from a High-frequency standpoint; in other words, too low to allow of their practical generation by the disruptive discharge of a condenser. A Faradic coil provided with a ribbon rheotome or a small sinusoidal alternator, giving a current of a maximum frequency of 5,000 per second being best adapted for the purpose.1
The Kinraide Coil charges its condenser with a current of high-amperage and relatively low voltage — the extremely high- potential of the High-frequency Current from this coil, resulting almost solely from the " step-up" transformation in the Tesla Coil. In most High-frequency Apparatus the increase of the potential is more or less equally divided between the "High- tension Transformer" and the "High-frequency," or Tesla Transformer. In Gaiffe's new X-Ray and High-frequency Ap- paratus, described in a preceding chapter, the alternating incandescent light current is raised from 104 volts to 60,000 volts, before being conducted to the condensers. Piffard's Hy- perstatic, when used with a large Holtz machine charges its con- denser at an even higher voltage.
The various machines designed and employed by the writer occupy a position between the two extremes respectively exem-
JNo absolute rule exists for the use of the terms "High" and "Low" Frequency: "Frequency" is a purely relative term. In the present volume the writer has, for the sake of convenience, defined a High-frequency Current as an alternating current which does not produce muscular contractions or affect the sensory nerves; it has, in other words, a frequency of over 10,000 per second; it happens that this frequency, which marks the limit of sensa- tion and motor re-action is the highest frequency obtainable by mechanical alternators, and we may therefore regard the term "High-frequency Current" as synonymous with "Oscillatory condenser discharge."
A full discussion of the relation between frequency and therapeutic effect is given in the second chapter on "Physiology."
94
HIGH-FREQUENCY CURRENTS
plified by the Piffard and Kinraide Coils. The capacity of the writer's condensers averages from twenty to thirty times that of Doctor Pijfard's Hyperstatic Transformer, but it is only one- fiftieth of the capacity used in the Kinraide Coil. The writer's
o
machines, therefore, generate currents of' a much lower fre- quency than those produced by the former, but of vastly greater frequency than that of the Kinraide Current.
The peculiar principle involved in the Kinraide Coil has been employed in the construction of two portable forms of High-
AMERICAN HIGH-FREQUENCY THERAPEUTICS
95
frequency Apparatus, which, although of different make, are so near alike in mode of action, and detail of design, that they may be appropriately described under a single heading. A fair idea of their general appearance and arrangement of parts may be
obtained from the illustrations in Figures 64 and 65. Each of these coils is designed for operation on the 104- volt alternating current, and consists essentially of a small closed-circuit trans- former similar to that used in the Kinraide Coil, except that the ratio of transformation is somewhat greater, the secondary
96
HIGH-FREQUENCY CURRENTS
current having a potential of 2000 volts. The condenser is very much smaller than that of the Kinraide Coil, and consequently produces currents of much higher frequenc}^ A single High- frequency Transformer is used, instead of two, as in the Kin- raide Coil ; but the principles are the same in both instruments ; the secondary consists of a single flat spiral, its center, or point of highest potential, terminating in an upright rod capped with a brass ball and insulated with a hard-rubber bushing. In the coil shown in Fig. 65 the spiral secondary just described is firmly
Fig. 66.— Kinraide Coil with Improved Spark-gap.
mounted on the same base with the transformer, spark-gap, and condenser, while in the second apparatus, it is arranged to fold inward at an angle of 90 degrees during transportation, the oscillating current from the condenser being conducted to the primary spiral by means of the two metal hinges. The objec- tionable feature of all apparatus of the Tesla-Thomson type has been the spark-gap, the corrosion and heating of its terminals seriously impairing the smoothness of the High-frequency Dis- charge and lowering the efficiency of the coil. In the original form of the Kinraide Coil this defect was of such a grave nature that many operators disposed of their apparatus at a considera- ble sacrifice, regarding it as totally impractical and unreliable.
AMERICAN HIGH-FREQUENCY THERAPEUTICS 97
This objectionable feature has been entirely eliminated in the Kinraide Coil shown in Fig. 66, which is provided with an im- proved spark-gap consisting of two brass tubes closed by plati- num caps, between the outer faces of which the discharge occurs; the brass tubes project from adjacent points in two cylindrical brass vessels filled with water, which conducts away the super- fluous heat of the spark-gap and renders the High-frequency Discharge from the secondaries full, continuous and steady. With the addition of this new spark-gap the Kinraide Coil has become a convenient and reliable apparatus for the generation of the X-Ray on alternating circuits, and for use in wireless teleg- raphy. It is probably the most efficient High-frequency Trans- former yet devised, as the power and volume of the secondary discharge is truly enormous as compared with the extremely small amount of electrical energy which the coil draws from the mains ; its relatively low frequency, however, renders this appa- ratus unsuitable for therapeutic purposes, while the two coils above described which have condensers of much smaller capacity produce currents which may be successfully employed in the treatment of disease. This reduction in condenser capacity, however, is made at the expense of efficiency, and for heavy X-Ray work a dangerously high amperage must be employed. For the general run of X-Ray and High-frequency work, how- ever, these coils are said to give very satisfactory results.
Several years ago the manufacturers of the Kinraide Coil, recognizing its inefficiency as a Therapeutic High-frequency Apparatus, introduced an instrument of similar construction but producing currents of much higher frequency, called the "Cyclone Coil.'7 (See Fig. 67.) This apparatus, which is no longer manufactured, is mentioned as an important example in the comparative study of High-frequency Coils; it uses a step- up transformer which raises the potential of the 104-volt alter- nating current to between five and ten thousand volts. Glass condensers are used instead of mica, and the two secondary coils (which are of the Kinraide type) produce a High-frequency Current sufficiently powerful for ordinary X-Ray work. Al- though these coils have been used with some success in thera- peutic work, they do not conform with the requirements which
98
HIGH-FREQUENCY CURRENTS
have been formulated by the writer as essential in a High- frequency Apparatus for physicians' use. This list of requisite characteristics embodies the writer's deductions from ten years' practical experience in the construction and therapeutic use of High-frequency Coils.
In the first place, the apparatus must be convenient and at- tractive in external appearance and capable of transportation
Fig. 67.— Cyclone Coil. (Portable form.)
without fear of injury to its working parts, or loosening of the wires connecting its various circuits.
Second, its transformers and condensers should be strongly made of the best obtainable material, and so perfectly insulated as to render the possibility of a breakdown exceedingly rare; but in the event of such an accident, the working parts should be easily and freely accessible, so as to enable the physician himself, in the absence of an electrical expert, to test out his own apparatus, locate the point at which the breakdown or interruption
AMERICAN HIGH-FREQUENCY THERAPEUTICS 99
of the circuit occurred, and, if necessary, remove the injured part for repairs.
Third, the current should be under perfect control, and the output in the secondary should be capable of regulation by the following methods: (a) the graduation of the current used to excite the primary coil of the step-up transformer by means of a Rheostat, or an adjustable inductive resistance; ("Choke Coil"). (b) By a variable spark-gap, provided with an easily accessible micrometer adjustment. The spark-gap should be self-cooling, and if at all noisy, should be completely enclosed in an asbestos- lined compartment. Its discharging surfaces should be easily removable for cleaning, and if the action of the spark causes them to corrode and wear away they should be so constructed as to be easily and economically replaced. It should be possible to run the apparatus at its maximum output for several hours continuously without overheating, and without evidence of fluctuation or loss of efficiency, (c) There should be some method of varying the potential of the discharge by the intro- duction or withdrawal of resistance in the external circuit; this may be accomplished by the use of a variable air-gap be- tween brass disks attached to the ends of sliding rods, by inter- posing glass plates, vacuum tubes, or insulated inductance coils in series with the patient in the external circuit.
Fourth, the various parts of the apparatus should be so pro- portioned that the High-frequency, High-potential Current from the Tesla Coil will possess the following characteristics- (a) Sufficient voltage or potential for the production of a full fine- grained "Effluve," at a distance of eight inches or more from the patient; the character of the discharge being such as to admit of this distance being reduced to three or four inches without danger of "arcing" the patient. In applying the brush discharge from the static machine, care must be taken to pre- vent the electrode from approaching too near to the patient's body, otherwise a bright spark will jump to the latter, causing a painful and unpleasant shock, with sharp muscular contractions. With Tesla Currents a somewhat different phenomenon occurs, the effluve being changed, not to a spark, but to an arc discharge, or an actual electrical flame, which often burns a small hole
100 HIGH-FREQUENCY CURRENTS
through the clothing and causes a painful "sear" or blister, before the electrode can be withdrawn to a safe distance. By- cutting out the secondary oscillations, by the interposition of ohmic resistance in the condenser circuit (" damping" the oscil- lation in other words), we can obtain from a Tesla Coil "Brush" and "Spark" Discharges closely resembling those produced by a static machine.1 (6) The currents should have a relatively high frequency with the shortest possible intervals between the different sets of oscillations, so that no sensation of shock or fluctuation will be felt when the patient is placed directly across the Tesla Circuit, or when the current passes through the pa- tient's body in series with an incandescent lamp, (c) The current should have a relatively high amperage, capable of bringing to full brilliancy an eight candle power incandescent lamp, when the latter is connected between the hands of two persons, one of whom holds in his free hand a terminal of the Tesla Coil. The current from a single terminal should be capa- ble of brilliantly illuminating a series of five or more Geissler Tubes when the latter form connecting links between the hands of an equal number of persons. In order to obtain the best therapeutic results, it is necessary that a current be employed which will manifest its potential, frequency, and amperage, by lighting lamps or vacuum tubes in the above manner, as efficiently as when the bulbs or tubes form a direct connection between the body and the Tesla terminal. There are many coils on the market which will excite a "vacuum electrode," connected to one of their pole's, so strongly that the surface of the patient's body will be blistered by a few seconds of contact with the electrode; while, if the patient be connected to the same pole by a metal handle, the above vacuum electrode will be scarcely illuminated if held in the hand of the operator and brought in contact with some part of the patient's body. The currents from such machines are useful only for the treatment of local and superficial lesions. With the best machines a Geissler Tube held in the hand of the operator, will glow when brought within a radius of four or five feet from a patient connected to one of the terminals of the Tesla Coil, (d) The Tesla Currents
1 See "Pseudo-Static Effects," in chapter on "High-frequency Modalities."
AMERICAN HIGH-FREQUENCY THERAPEUTICS 101
should be of sufficient volume to produce X-Rays capable of giving a clear fluoroscopic picture of the thorax, shoulder-joint, etc., and of giving a satisfactory skiagraphic negative of the bones of the hand in one second or less, when the machine is drawing not more than 500 watts from the mains.
The exact details of construction necessary for the production of an apparatus having the above ideal characteristics can be determined by experiment only, and the writer's efforts in this direction were but partially successful until about two years ago, when he was fortunate enough to discover a combination producing results of the above character. The fortuitous cir- cumstances which led to these results, while in some degree accidental, were mainly brought about through an exhaustive comparative study of the various types of High-frequency Apparatus that had been produced up to that time, including the writer's earlier models. For a long time it seemed to be impossible to produce currents which should be equally satis- factory for therapeutic use and X-Ray purposes. The Kin- raide Coil produced X-Rays of great power and penetration, but has been shown to be impractical for therapeutic use: the writer's earlier apparatus, on the other hand, while seemingly ideal as a generator of Therapeutic High-frequency Currents was decidedly inferior to the Kinraide Coil for X-Ray work. The successful production of one of these requirements seemed possible only by sacrificing the second end in view: indeed, the two seemed incompatible. There is reason to believe that other investigators reached the same conclusion. For example, the "Jackson Coil," invented jointly by Mr. Kinraide and Mr. Howard Jackson, which was an ideal instrument for High-fre- quency Therapeutics was frankly avowed by its manufacturers to be unsatisfactory as a generator of X-Rays, for other than therapeutic purposes. This coil, which is no longer manufac- tured, embodied a number of new and unique features which are worthy of a brief description. The High-frequency Trans- formers are of the "Kinraide type," but the secondary spirals contain fewer turns of wire, and the ratio of voltage between the primary and secondary circuits is much smaller than in the Kinraide Coil. In the latter the high potential is obtained
102
HIGH-FREQUENCY CURRENTS
almost entirely through the transforming action of the High- frequency Coils, while in the Jackson Apparatus the voltage is raised for the most part1 by the "step-up" transformer in the Low-frequency Circuit: the Jackson Condenser has but small
Fig. 68. — Spark-gap of Jackson Coil.
fraction of the capacity of that of the Kinraide Coil, and conse- quently discharges at a much higher frequency ; as the charging circuit has a potential of from 30,000 to 40,000 volts, the am- perage at the spark-gap is much less than in the Kinraide Coil; consequently much less heat is evolved and water cooling devices are unnecessary. The spark occurs between the edges
3 (
^<Z
B C
Fig. 69. — High-frequency Spark-gaps. A, Kinraide Coil (improved). B, Cyclone Coil. C, Jackson Coil.
of two horizontal bars of iron about two inches long, square in section, and about one-half inch in diameter; the gap between them may be varied by a micrometer screw and the jaws which support the bars are each provided with a series of thin copper
AMERICAN HIGH-FREQUENCY THERAPEUTICS 103
plates to radiate the heat; if the edges of the bars become blunted or corroded, the latter may be withdrawn, and turned through an angle of 90 degrees, so as to bring a fresh edge into position. (Fig. 68.) This spark-gap gives excellent results in the Jackson Coil but it is not satisfactory when employed in a con- denser circuit of low voltage, such as is used in the "Cyclone Coil" for example. (See Fig. 69.) In the latter instrument the spark takes places between the parallel faces of iron disks about three- quarter inches in diameter; these are mounted with radiating
Fig. 70. — The Author's "Special Hercules" Coil.
wings, as in the Jackson Gap. The general appearance and con- struction of the spark-gaps of the Kinraide Coil, Cyclone Coil and Jackson Coil are shown in the illustration (Fig. 69). The High-frequency Transformers of the Jackson Coil are entirely separate from the rest of the apparatus and are supported by an upright wooden mast which is either fixed to the back of the cabinet, or mounted independently in an iron tripod as in Fig. 71, and the primaries of the High-frequency Coils are so arranged as to allow of one or both secondaries being used, so that the effects of a Testa Coil or an Oudin Resonator may be obtained as desired. The greatest value of the Jackson
104
HIGH-FREQUENCY CURRENTS
Coil lies in its beautiful "Effluve" which is full, of fine grain and free from fluctuation ; while it may be controlled or gradu-
Fig. 71. — Jackson Coil with Separate Secondaries.
ated with the greatest nicety by the micrometer spark-gap, and by an adjustable Rheostat in the Low-frequency Circuit. Heavy "d'Arsonval effects" are obtained from the Jackson Coil by
AMERICAN HIGH-FREQUENCY THERAPEUTICS 105
diverting the condenser discharge from the Tesla Circuits to a heavy spiral solenoid called the "Thermo-Faradic Coil," which will produce as high as 3,000 milliamperes of current.
In the ensuing chapter the writer will describe his latest High-frequency Coils, which conform to the list of requirements enumerated in the preceeding pages.
CHAPTER VIII
MODERN HIGH-FREQUENCY APPARATUS OF THE AMERICAN TYPE
Tesla-Thomson Coils
The machines which the writer employs in his practice at the present time embody the most recent deductions from his clinical and experimental researches. They are of three different models, being denominated by their manufacturers as the "Hercules/7 the "Ajax," and the "Hercules Universal"; the first two are of the " Testa type" for use on alternating electric light currents; the third or last being a direct or continuous cur- rent machine, although arranged to work equally well on an alternating supply. The term ''Universal'' is employed not only from the adaptability of the apparatus as regards exciting currents, but from the fact that it combines in a single instrument a Ruhmkorjf Coil, Resonator, and Testa Coil. The details of the "Hercules Universal" will be discussed under a future heading. Of the two alternating machines, the "Ajax" Coil is probably the more important from the standpoint of the general profession. The "Hercules Apparatus" is of a very elaborate and expensive construction and is designed primarily for the electro-therapeutic specialist. The "Ajax" Coil of the conventional type is shown in Fig. 72. Fig. 73 shows a larger and more pretentious type known as the "Ajax special." These two machines are identical in so far as their transformers, condensers, spark-gaps and Testa Coils are concerned, but the "Special" model involves a con- venience of arrangement, easy accessibility, and range of useful- ness, not found in its simpler prototype. It is provided with a heavy solenoid producing powerful "d'Arsonval" and "Thermo- Faradic currents," has a stepped inductance for the graduation of its primary current, and may be equipped, if desired, with a separate transformer for the production of cautery and diagnostic light currents.
106
MODERN AMERICAN HIGH-FREQUENCY APPARATUS
107
The development of the "Ajax" Special, and the arrangement of its various details is the work of Mr. John R. Parker (Superin- tendent of Construction for the Electro-Radiation Company) to whom the writer is indebted for many new ideas and practical suggestions employed in the production of his latest types of apparatus.
Fig. 72.— The Author's "Ajax Coil."
In the "Special Ajax" the 104 volt alternating current is passed through a conventional closed-circuit transformer, in which the potential is raised to about 10,000 volts. The amount of current delivered from the transformer is determined by the "stepped" inductance above-mentioned, which admits either one, two, or three and a half amperes to the primary coil; according to whether the plug on the end of the service cord is attached to
108
HIGH-FREQUENCY CURRENTS
the first, second or third pair of pins (see Fig. 74) . The capacity of the condenser is such that a frequency of about one million (1,000,000) per second is produced in the Tesla and d'Arsonval
Fig. 73.— The "Ajax Special Coil."
MODERN AMERICAN HIGH-FREQUENCY APPARATUS
109
Circuits. The condenser consists of a number of sections, each of which contains five pairs of glass plates coated with tin-foil and firmly imbedded in a wax composition; this construction allows of the removal of a portion of the condenser in the rare event of one of the glass plates being shattered by rough handling of the machine during transportation, and, inasmuch as the machine will work satisfactorily on a condenser of less than its normal capacity, the damaged section may be shipped to the factory for repairs. The spark-gap is similar to that emploj^ed in the Cyclone coil, previously described (see Fig. 69), except that the iron disks of the latter are replaced by brass pieces faced with pure silver. The coil which the writer employs in his practice at the present time, is provided with a spark-gap similar in principle to the above, but of an improved construction, involving several new and important features; the movable
|
o |
o |
o |
|
1 |
2 |
3 |
|
o |
o |
o |
Fig. 74. — "Theater Plug," for varying current strength on "Cyclone" and "Ajax Special Coils."
member is operated by a cam or eccentric, which varies the spark-gap from zero (or contact), to a maximum length of five millimeters, corresponding to a rotation of the cam-shaft through an arc of 180 degrees. The hard-rubber adjusting knob is attached to the end of the cam-shaft which projects through the door of the cabinet, and is provided with a metal hand, or pointer, moving in front of a scale which indicates the length of the spark-gap in millimeters and tenths of a millimeter. By turning the knob to the extreme right, bringing the hand opposite the letters "TJ. V." on the scale, a gap of five millimeters is formed, which is too great a distance for the current to traverse; con- sequently no spark passes, and the apparatus may then be used to operate an ultra-violet lamp which is connected to the con- denser circuit by means of suitable terminals. (Fig. 75.)
The "High-frequency" or "Tesla-Thomson" Transformer em- ployed in the "Ajax" machine, consists of a primary composed
110 HIGH-FREQUENCY CURRENTS
of a small number of turns of coarse wire wound upon a tube about six inches in diameter, which is slipped over the center of the secondary coil, which is formed of a great many turns of extremely fine silk insulated wire, closely wound upon a tube four inches in diameter and about two feet in length. The annular space between the primary and secondary tubes contains a number of layers of flexible mica and the High-frequency Transformer thus assembled, is permanently embedded in solid wax in a suitable wooden box, the primary and secondary terminals being brought through the walls of the latter by rubber insulating bushings. The High-potential High-frequency Cur- rent is led from the "Teste," secondary to a pair of insulated terminals surmounted by brass balls; a third terminal called
the "dummy" is fixed on an in- sulated pillar midway between the two active terminals, and consists of a brass disk co- operating with a similar disk on the end of a sliding rod in the left-hand terminal; a sec-
Fig. 75. — The Author's New Graduated Olid sliding rod in the light- Spark-gap, for Aiax Coils, i i j. -i j- F & F' J hand terminal ending in a
small brass ball, its counterpart being fixed to the right- hand side of the "dummy." When the machine is in operation, and the right-hand rod pushed into contact with the "dummy," a brilliant purple "Effluve" will be formed between the brass disks, when the latter are separated by a gap of three or four inches; if the disks be in contact, and an air gap formed on the right-hand side of the "dummy," between the two brass balls, the discharge will occur in the form of a flaming "Arc," or pencil of light. The uses of these triple terminals to produce various modifications in the character of the secondary current will be considered in detail in a later chapter.
The "Hercules," shown in Fig. 76, closely resembles the "Ajax" in so far as its electrical construction is concerned, except that a rotaiy spark-gap is employed instead of a sta- tionary one. The former, shown in Fig. 77, consists of a brass disk mounted on the end of the shaft of a small alternating
MODERN AMERICAN HIGH-FREQUENCY APPARATUS
111
motor, being insulated from the latter by a heavy fiber bushing. The periphery of the disk is divided into rectangular teeth, one- half inch in width, by slots of the same width and depth; the thickness of the disk is about one-eighth inch. The current
Fig. 76. — The Author's "Hercules" High-frequency Apparatus.
from the condenser is admitted to the disk by means of a graphite brush, which presses against a graphite button held in a cup- shaped depression in the exact center of a rotating disk. The spark-gap is formed between the upper edge of the disk and a brass ball on the end of a vertical rod, which projects through
112
HIGH-FREQUENCY CURRENTS
=C
2
a.
3C
4
-if
H
a threaded bushing in the top of the cabinet and terminates in a hard-rubber adjusting knob. The writer has recently improved his rotary gap by substituting for the threaded ball-tipped rod a disk of nickel or silver mounted eccentrically upon the lower end of a vertical rod, mounted not in the plane of the disk but about one inch in front of it. The spark, instead of following a vertical path between the upper edge of the revolving disk and the lowest point of the brass ball, traverses a horizontal gap between the outer surfaces of the revolving teeth and the inner edge of the silver disk; the latter is somewhat rounded on its edges, and is about three-fourths inch in diameter and one- fourth inch in thickness ; it is attached to the rod by means of a
threaded hole midway between its center and periphery. The rod turns by means of a knob, as in the former model, but its bushing is not threaded, and brass collars fixed to the rod above and below the bushing prevent all motion of the silver disk except in a horizon- Fig. 77.— The Author's Improved tal plane. A pointer attached to Rotary Spark-gap. $& krass r0(j just below the rubber
"*<£*to ButSft BSphhe knob. mov.es j» front °f a cu«ed Brush, e, Silver Disk Mounted scale and indicates the length of
Eccentrically. ,, ,, , ., , .
the gap m the manner described in connection with the "Ajax" machine. The rotary spark-gap just described does not appear to operate satisfactorily on all types of High-frequency Apparatus, but it is peculiarly adapted to the particular voltage, amperage and frequency of the con- denser discharge in the " Hercules" machine. It appears to produce a peculiar effect on the High-frequency Current which renders the latter more efficient for certain therapeutic purposes. This action will be discussed more fully in an ensuing chapter. The frequency of the "Hercules" machine is slightly less than that of the "Ajax," as the condenser capacity is greater than in the latter machine. The voltage of the Tesla current in the "Hercules" is distinctly higher than in the "Ajax" and the machine draws a larger amount of electricity from the mains.
MODERN AMERICAN HIGH-FREQUENCY APPARATUS 113
The perfect manner in which the heat is dispersed by the Rotary Spark-gap makes it possible to operate the "Hercules" machine continuously for hours without danger, or loss of efficiency. The "Hercules" Low-frequency Transformer, while similar in action to that of the "Ajax" is of a more complicated and expensive construction. Aside from the points above enumer- ated, the "Hercules" coil differs from the "Ajax Special" solely in its more elaborate and expensive cabinet and mountings.
CHAPTER IX
MODERN AMERICAN HIGH-FREQUENCY APPARATUS, FOR "DIRECT
CURRENT" USE
Many physicians who prefer to employ the " Tesla-Thomson" type of High-frequency Apparatus have been handicapped by their inability to obtain an alternating current service. In the cen- tral portions of large cities and in occasional small ones, the direct or continuous current is the only source of supply. This is especially true in England and on the Continent. The first attempt to devise a means to adapt Tesla Apparatus to direct currents was made in connection with the original "Knott High- frequency Coil," and involved the use of a slate wheel bearing metal segments revolving against carbon brushes, and acting as a commutator which changed the direct current to an interrupted alternating current; but the slate wheel rapidly wore out, the brushes required frequent adjustment, and the device was ex- tremely noisy and cumbersome. Despite these facts, the writer employed a break-wheel of this type for several years, all of his clinical work at the Boston Dispensary being carried out by means of such an apparatus. When the " Strong-Ovington machine" was placed upon the market, it became evident that some other means must be found for alternating the direct current, and, after some experiments, it was decided to adopt what is known as a "rotary converter." This apparatus (see Fig. 78) is a "shunt-wound" direct current motor, with the armature tapped at two diametrically opposite points connected respectively to two insulated "collector rings," which are usually mounted on the end of the armature shaft opposite to that which carries the commutator. Two carbon brushes bear against the revolving rings, and from these brushes a true alternating current may be obtained — the number of cycles per second corresponding to the number of revolutions of the arma-
114
MODERN AMERICAN HIGH-FREQUENCY APPARATUS 115
ture during the same interval of time. The voltage of this alternating current is usually about four-fifths that of the original direct current and it is therefore necessary to employ a slightly higher ratio of transformation in the step-up transformer, in order that the condenser may be charged at the same potential as when the machine is operated on the ordinary alternating incandescent light current. In the larger types of rotary con- verters it is possible to obtain an alternating current identical in voltage with the direct current which excites the converter; this is accomplished by the use of a second set of armature windings, insulated from the direct current circuit; and the instrument becomes in reality a " Motor Dynamo" or "Motor-
E
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direct alt.
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i
x
Fig. 78. — Rotary Converter, Excited by a 110 Volt Direct Current, and Generating an Alternating Current of 80 Volts.
Generator." This construction greatly increases the expense of the converter, and, unless the High-frequency Coil is to be used on both direct and alternating currents, it will be simpler to adapt the transformer for the lower voltage of the ordinary type of rotary converter.
Physicians whose knowledge of High-frequency Currents has been derived from European textbooks will be familiar only with forms of apparatus in which the Ruhmkorff coil is employed, such as have been described in a preceding chapter. A number of American manufacturers have introduced outfits of the above type, some of which are equal if not superior to the productions of the best European makers. Examples of this type of appar-
116
HIGH-FREQUENCY CURRENTS
atus are shown in Figs. 79 and 82. The Ruhmkorff coils in these outfits are of similar construction, being enclosed in a cherry or mahogany box filled with a jelly-like insulating medium. Coils of this construction, all things being considered, are less liable to injury or breakdown than those of the conventional type in which the secondary is protected by a thin sheet of hard rubber. The two coils above-mentioned are provided with large mica
Fig. 79. — " Scheidel-Western " Coil for Exciting High-frequency Apparatus.
condensers of variable capacity mounted in a compartment beneath the coil. When used with a "Wehnelt" or "Electro- lytic" interrupter, as in Fig. 82 (which shows a Ruhmkorff High- frequency Apparatus arranged for use on the alternating electric light current), the above-mentioned mica condenser is not in- cluded in the circuit; in the arrangement shown in Fig. 79, how- ever (adapted for use with the direct current) in connection with a mercury jet or turbine interrupter, the condenser must be
MODERN AMERICAN HIGH-FREQUENCY APPARATUS 117
employed . The ' ' resonators ' ' in the above outfits are of the conventional European type, and their action and adjustment are similar to those previously described.
In Fig. 81 a slightly differ- ent type of High-frequency Apparatus is shown, which combines the resonance prin- ciple of Oudin with the in- ductive action of the Tesla- Thomson Coil; it is called an " Inducto-Resonator," and, in the opinion of the writer, possesses some advantages over the conventional " Oudin Resonator."
In Fig. 82, is shown an American High-frequency outfit which, while employ- ing the regular Oudin- d'Arsonval system shows many radical departures from the customary arrangement of the parts in the European appa- ratus. The resonator and solenoid are both enclosed and mounted horizontally above the Ruhmkorff Coil, which is embedded as those above described. The inter- rupter, which is of the electrolytic type, is enclosed in a cabinet on the side of which is a large rheostat for varying the primary current.
This apparatus is said to work well on either direct or alter- Fig. 81.— "Inducto-resonator," in- nating circuits and possesses a
volving Induction, as well as . . . ,. M ,.
Resonance. marked advantage in that the
Fig. 80.— "Scheidel- Western" High- frequency Apparatus, for Use with Coil Shown in Fig. 79.
118
HIGH-FREQUENCY CURRENTS
Ruhmkorff and High-frequency Coils are combined in a single unit.
During the past few years a number of High-frequency Ma- chines have been placed upon the market, which combine a
Fig. 82. — Meyrowitz High-frequency Apparatus.
Ruhmkorff coil with a High-frequency Transformer of the " Tesla-Thomson" type. The currents produced by this com- bination differ in a number of respects from those obtained from a typical Testa apparatus (such as the writer's "Ajax" machine, for example), nor are they similar in character to currents from
.MODERN AMERICAN HIGH-FREQUENCY APPARATUS
119
an Oudin resonator ; they are, however, suitable for therapeutic use in practically the same manner and for the same conditions as the currents above-mentioned. A well-known example of this class of apparatus in the so-called uCole Coil," shown in
Fig. S3. — The "Cole Coil," for X-Ray and High-frequency Generation.
Fig. 83; the general design and arrangement of parts is the work of Dr. Lewis Gregory Cole, of. New York City. The High-frequency Coil is a modification of Piffard's "Hyperstatic Transformer," with its primary windings altered so as to adapt
120 HIGH-FREQUENCY CURRENTS
it for use with a Ruhmkorff Coil. The latter coil is mounted in a glass case, surmounting a square wooden cabinet containing the electrolytic interrupter. An ammeter is permanently fixed to the front of the cabinet and indicates the amount of current passing through the primary circuit. By means of a pulley, operated by a handle at the side of the glass case, the connection is made between the Ruhmkorff secondary and the Piffard High-fre- quency coil, which is mounted in the manner shown in the illus- tration. Multiple spark-gaps are provided for X-Ray purposes, and when equipped for use on the alternating current a " Villard Valve" and "Oscilloscope" are included in the outfit. In addi- tion to the two Leyden Jars belonging to the Hyperstatic, there is a small accessory jar for use with the "Piffard Ultra-violet lamp." The frequency of the currents from the Hyperstatic is about the same as when a Static machine is used to charge the condensers. A convenient feature of this outfit is the use of steel tapes to connect the coil with the X-Ray tube, or electrodes ; when not in use, these tapes are automatically coiled up like pocket tape- measures.
Heinze's apparatus is in many ways similar to the one just described as it consists of a Ruhmkorff Coil with its inter- rupter, rheostat, etc., combined with a High-frequency Trans- former of the Tesla-Thomson type. The latter coil, however, is considerably larger and of greater power than the "Hyper- static"; and is of proportionately lower frequency, the capacity of its condensers being at least four times that of Piffard's Ap- paratus. The important feature of this outfit is its mechanical interrupter, which is one of the best instruments yet devised for breaking the primary current of a Ruhmkorff coil. In the lower part of the cabinet is mounted a small transformer for cautery, and diagnostic light purposes.
The writer's contribution to the list of outfits of the "Ruhm- korff-Testa" type, is the so-called "Hercules Universal," previ- ously alluded to (see Fig. 84). In the lower part of the cabinet is a wooden box containing a twelve-inch Ruhmkorff coil, suitably embedded, which is wound so as to produce secondary currents of exceptionally high amperage. In the same compartment with the coil is an improved electrolytic interrupter,. recently invented
MODERN AMERICAN HIGH-FREQUENCY APPARATUS 121
by the author, so arranged as to be practically noiseless, and reg- ulated by means of a vertical rod ending in a knob on top of the cabinet. (See Fig. 85.) A Testa-Thomson coil of peculiar design, is mounted between the top of the cabinet and the plate-glass table which supports the Mexican onyx pillars of the triple terminals. The arrangement of the apparatus is such that, normally, the Ruhmkorff Secondary Terminals are connected to
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a
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Fig. 84. — The "Hercules Universal," the Author's latest Apparatus for Obtaining both "Ruhmkorff" and True "Tesla" Currents, from either Direct or Alternating Service.
the High-frequency Circuit ; when it is necessary to employ the Ruhmkorff current directly (as in the excitation of X-Ray tubes, for example), the two insulated knobs at either side of the central panel are pulled out, like the " Stops" of an organ, exposing the binding posts of the secondary circuit and simul- taneously breaking the connection between the latter and the High-frequency Apparatus. The writer believes his apparatus to be unique in that a multiple-plate condenser and short spark- gap are substituted for the Leyden Jars and long, high-resistance
122
HIGH-FREQUENCY CURRENTS
gap employed in all other forms of " Rukmkorff High-frequency Apparatus."
When operated on the alternating current the electrolytic interrupter may be dispensed with (a suitable short-circuiting switch being provided for the purpose), and it would then be difficult to distinguish between the High-frequency currents and a true Tesla-Thomson current from an apparatus with a closed-
Fig. 85. — The Author's Improved Electrolytic Interrupter.
I. — General Construction. II. — Details of Anode.
a, Porcelain Tube; b, Threaded Copper Wire; c, Metallic Mercury which keeps the point of ("b") amalgamated by flowing around the spiral groove of the screw-thread.
circuit transformer. Even when operated on a direct current, with the interrupter in circuit, the High-frequency Currents from the "Hercules Universal7' are practically identical with those of its alternating prototype except for exciting Crooke's Tubes in skiagraphic work; and as the Secondary Rukmkorff Current is available for the latter purpose, and as it gives results decidedly superior even to those obtained with an alternating Current High-frequency Apparatus, it will be readily seen that this difference is of no practical importance. For all therapeutic
MODERN AMERICAN HIGH-FREQUENCY APPARATUS 123
purposes, including X-Ray therapy, the High-frequency Cur- rents from the above machine are of equal value and are em- ployed in the same manner as the currents from a standard "Ajax" or "Hercules" Coil.
One very great advantage of the "Hercules Universal" is that it dispenses with the cumbrous and costly "Rotary Converter"; it may also be commended from the fact that it may be operated, as desired, on either an alternating, or a direct current. For those who are desirous of comparing the action and therapeutic value of High-frequency Currents of the " Tesla-Tho?nson" type with those of Oudin, or d'Arsonval, the above outfit is especially useful, as it readily admits of the use of separate solenoids and resonators, which may be used alternately with the Tesla Coil by the employment of the two "organ stops," above described.
This apparatus, which will be placed upon the market within the next few months is the product of several years research and experiment on the part of the author, who formerly believed it to be practically impossible to produce from a Ruhmkorff outfit High-frequency Currents of the same general character as those obtained from a typical Tesla-Thomson Coil, excited from an alternating current transformer.
The final solution of the problem was obtained through the use of a Tesla-Thomson coil of a peculiar and unique winding, in connection with an especial form of spark-gap, and a Ruhm- korff Coil giving secondary currents of high amperage.
CHAPTER X
ANALYSIS AND COMPARISON OF HIGH-FREQUENCY CURRENTS FROM DIFFERENT FORMS OF APPARATUS
In order to obtain an intelligent idea of the physiological and therapeutic action of a given type of High-frequency Current, it is necessary to accurately analyze the method by which the current is generated, and to study it from a physical and mathe- matical standpoint. The "Graphic Method," previously ex- plained, will be found of great assistance to a clear comprehen- sion of the difference between the currents generated by the various types of apparatus which have been described in the preceding chapters.
The factors which determine the qualities of a High-frequency Current are as follows :
(a) Capacity of the Condensers.
(&) Potential or Voltage of the Charging Current.
(c) Rate of Charge, or the number of Primary Discharges per second.
(d) Inductance of the Discharging Circuit, depending upon the size of wire, and the diameter and number of turns in the Solenoid, or Primary Tesla Coil.
(e) The length of the Spark-gap and the nature of its Terminals and the rapidity with which these Terminals conduct away the heat generated at each Primary discharge.
(/) The Diameter and number of Turns per inch and the total length of the Resonator, or Secondary Tesla Coil, as com- pared with