CONTENTS.

[CHAPTER I].
COIL CONSTRUCTION.
Construction of Ruhmkorff Coils. Sizes of Wires. Winding of Primary and Secondary. Assembling. Connecting Up. Insulation. Coils in Series. Oil Immersed Coils. "Tesla" Coil. Disruptive "Tesla" Coil. Coils for Gas Engines. Spark Coils. Resistance Coils. General Remarks on Coils. The Testing of a Coil for Polarity. Failure to Work. Medical Coils. Medical Coil with Tube Regulation. Medical Coil with Interchangeable Secondaries. Bath Coils1-64
[CHAPTER II].
CONTACT BREAKERS.
Construction of Contact Breakers. Various Forms ofSimple Contact Breakers. The Mercury Vibrator. PolechangingVibrator. Wehnelt Interrupter. Dessauer Contact Breaker. Steel RibbonInterrupter. Contact Breakers in Vacuo. Queen Contact Breaker.Adjustable Contact Breaker for Medical Coils. The Queen Contact Breakerfor Large Coils, Adjustable Cone Vibrator. Contacts65-91
[CHAPTER III].
INSULATIONS AND CEMENTS.
Selection of Insulating Materials. Mineral Oil.Paraffin Wax. Resin Oils. Beeswax. Shellac Varnishes. Silk. InsulatingCompounds92-98
[CHAPTER IV].
CONDENSERS.
Construction of Condensers. Leyden Jar.Glass Plate Condenser. Paper Condensers. Series Condenser. Rolled-UpCondensers. Adjustable Condensers. Application of Condensers99-119
[CHAPTER V].
EXPERIMENTS.
Luminous Effects Obtained by Means of a Ruhmkorff Coil.Materials Used. Spark Experiments. The Luminous Pane. Luminous Designs,etc.120-130
[CHAPTER VI].
SPECTRUM ANALYSIS.
Color Produced by Burning Different Metals. TheSpectroscope Shown in Connection with the Coil. The Screen. The ColorSpaces in the Solar Spectrum. Color Values131-139
[CHAPTER VII].
CURRENTS IN VACUO.
Different Forms of Mercury Air Pumps. Geissler Tubes.Discharges in Vacuo. Characteristic Colors of Different Gases in Tubes,etc.140-152
[CHAPTER VIII].
ROTATING EFFECTS.
Effects of Discharges in Rotating Tubes. Constructionof Rotating Wheels. Arrangement of Tubes, etc.153-163
[CHAPTER IX].
GAS LIGHTING.
The Application of the Ruhmkorff Coil for Lighting Gas.Gas Lighting in Series. Gas Lighting in Multiple. Gas Lighting Diagram.Jump Spark Burner. Automatic Burners164-177
[CHAPTER X].
BATTERIES FOR COILS.
The Selection of Suitable Batteries. Open CircuitCells. Closed Circuit Cells. Description of Cells. Formulæ forSolutions for Different Kinds of Batteries. The Grenet Battery. FullerBattery. Gravity Battery. Dun Cell. Gethins Cell. Gordon Battery. NewStandard. Edison-Lalande Cell. Dry Batteries. Dry Cell Construction,etc.178-199
[CHAPTER XI].
STORAGE OR SECONDARY CELL.
Construction of a Storage Cell. Connecting Up Cells.Charging Storage Batteries. Diagram for Charging from Dynamo Usinga Rheostat. Diagram for Charging, using Lamp instead of Rheostat.Charging from. Primary Batteries. Testing Solutions. Setting Up theStorage Cell. The Harrison Cell. The "U. S." Storage Cell, etc.200-223
[CHAPTER XII].
TESLA AND HERTZ EFFECTS.
Currents of High Frequency. Electric Resonator. The"Tesla" Effects. Coil Connected to Discharger. High Frequency Currentsin Electro-Therapeutics, etc.224-234
[CHAPTER XIII].
THE "ROENTGEN" RAYS AND RADIOGRAPHY.
General Arrangement of Connections for Coil and CrookesTube for Making X Ray Negatives. The Fluoroscope. Phosphorus Tube. TheQueen Self-Adjusting Crookes Tube. General Remarks, etc.235-247
[CHAPTER XIV].
WIRELESS TELEGRAPHY.
Arrangements of Simple Circuits of Coil and Coherer forReceiving and Sending Messages. The Coherer. Carbon Coherer. Cohererwithout Filings. Aluminum Coherer. Steel Ball Coherer. The Oscillator.Clarke's Oscillator. Triple Oscillator. The Coil. Translating Devices.Air Conductor, etc.248-265
[Index]266
[Bibliography]270

CONTENTS OF TABLES.

PAGE
Good Proportions of Core Lengths[7]
Table of "Secondary" Windings[24]
Polarity Tests[45]
Dimensions for Different Spark Lengths[50]
Table Showing Resistances and Feet per Pound of Copper and German Silver Wire[64]
Specific Inductive Capacity[119]
Wave Lengths and Temperatures[138-139]
Table of Relative Costs of Materials[191]

LIST OF ILLUSTRATIONS.

Frontispiece, The Queen 45″ Spark Coil.

FIG.PAGE
[1].Section of Coil4
[2].Insulating Tube Ends10
[3].Sectional Winding11
[4].Section " First Method12
[5]. "" Second Method13
[6].Proportional Diagram of Coil15
[7].Section Winder, End View17
[8]. "" Face View17
[9].Assembly of Coils18
[10].Polechanging Switch31
[11].Disruptive Tesla Coil35
[12].Spark Coil for Gas Engine38
[13].Reproduction of a 32-inch Spark47
[14].Simple Medical Coil53
[15].Connections for Simple Medical Coil55
[16].Interchangeable Medical Coil56
[17].Vibrator for Medical Coil60
[18].Simple Contact Breaker65
[19].Imperfect Form of Contact Breaker67
[20].Superior Form of Contact Breaker67
[21].Spotteswoode Contact Breaker69
[22].Polechanging Contact Breaker74
[23].Wehnelt Interrupter78
[24].Ribbon Vibrator81
[25].Queen Contact Breaker82
[26].Adjustable Contact Breaker86
[27].Cone Contact Breaker88
[28].Coil Head Contact Breaker89
[29].Leyden Jar101
[30].Plate Condenser102
[31].Arrangement of Condenser Plates104
[32].Condenser Charging, First Method110
[33].Condenser Charging, Second Method112
[34].Adjustable Condenser118
[35].Spark between Balls125
[36].Short Spark between Balls125
[37].Sparkling Pane125
[38].Luminous Design128
[39].Electric Brush128
[40].Spectrum—Solar132
[41].Spectroscope and Coil133
[42].Simple Air Pump141
[43].Geissler Air Pump144
[44].Sprengel Air Pump144
[45].Solution Tube150
[46].Fluorescent Bulbs150
[47].Ruby Tube—Crookes150
[48].Iridio-platinum Tube—Crookes151
[49].Revolving Wheel154
[50].Tube Holder157
[51].Side View of Wheel157
[52].Geissler Tubes160
[53].Triangle on Disc161
[54].Maltese Cross on Disc161
[55].Gas Lighting Circuit165
[56].Connections for Gas Burners169
[57].Bartholdi Automatic Burner172
[58].Connections for Automatic Burner174
[59].The Grenet Cell180
[60].The Fuller Cell184
[61].The Gethins Cell193
[62].Lead Plate for Storage Cell201
[63].Wooden Separator201
[64].Charging with Rheostat207
[65].Charging with Lamps207
[66].Harrison Electrodes211
[67].Hydrometer221
[68].Hertz Resonator227
[69].Tesla Circuit229
[70].Tesla Cut Out231
[71].Tesla Cut Out, Top Plan232
[72].Circuit for X Ray Apparatus237
[73].Queen's Self-Regulating X Ray Tube240
[74].Transmitter for Wireless Telegraphy250
[75].Receiver for Wireless Telegraphy252
[76].The Branley Coherer254
[77].Clarke's Oscillator259
[78].Triple Oscillator259
[79].Air Wire Insulators263