CHAPTER I.

§ 1. Secondary Current by Induction. No FARADAY Increased E. M. F.

2. Electric Spark and Increased E. M. F. PAGE by Induced Current.

3. Spark in Secondary Increased by FIZEAU Condenser in Primary.

4. Atmosphere around an Incandescent Live VINCINTINI Wire.

5. Magnetizing Radiations from an Electric HENRY Spark.

6. Arcing Metals at Low Voltage. FARADAY

7. Non-arcing Metals at High Voltage. WURTS Practical Application.

8. Duration of Spark Measured. WHEATSTONE

8_a_. Discharge—Intermittent, Constant, and FEDDERSEN Oscillatory—by Variation of Resistance.

9. Musical Note by Discharge with Small FARADAY Ball Electrodes. Invisible Discharge.

9_a_. Pitch of Sound Changed by Approach of FARADAY and Conductor Connected to Earth. MAYER

10. Brush Discharge. Color. Striæ. Nitrogen FARADAY Best Transmitter of a Spark, and its Practical Bearing in Atmospheric Lightning. Cathode Brushes in Different Gases.

11. Glow by Discharge. Glow Changed to FARADAY Spark. Motion of Air. Apparent Continuous Discharge during Glow.

12. Spark. Solids Perforated. LULLIN

13. Spark. Glass Perforated. Holes Close FAGE Together. Practical Application for Porous Glass.

14 and Spark. Penetrating Power. Conducting KNOCHENHAURER, 14_a_. Power of Gas. Relation of E. M. F. to BOLTZMANN, Pressure of Gases. Discharge through THOMSON Hydrogen Vacuum Continued with Less (KELVIN), Current than that Required to Start MAXWELL, it. VARLEY, HARRIS, and MASSON

15. Dust Particles or Rust on the GORDON Electrodes Hasten Discharge.

16. Where the Distance is Greater, the THOMSON Dielectric Strength is Smaller, Both (KELVIN) Distances Being Minute.

17. Discharge through Gases under Very High CAILLETET Pressures. Increased Dielectric Strength.

18. Discharges in Different Chemical Gases FARADAY Variably Resisted.

19. Gas as a Conductor. Molecule for THOMSON, J. J. Molecule, its Conductivity Greater than that for Gases.

20. Relation of Light to Electricity. The BOLTZMANN, Square Root of the Dielectric GIBSON, Capacity Equal to the Refractive BARCLAY, Index. HOPKINSON, and GLADSTONE

21. Hermetically Sealed Discharge Tubes PLÜCKER and with Platinum Leading-in Wires. GEISSLER

22. Luminosity of Discharge Tubes Produced GEISSLER by Rubbing. Increased by Low Temperature.

23. Different Vacua Needed for Luminosity ALVERGNIAT by Friction and by Discharge.

24. Phenomena of Discharge around the Edges STEINMETZ of an Insulating Sheet.

25. Highest Possible Vacuum Considered as a MORGAN Non-conductor.

26. Constant Potential at the Terminals of DE LA RUE and a Discharge Tube. MÜLLER

26_a_. Polarity of Discharge-tube Terminals in KLINGENBERG Secondary of Ruhmkorff Coil. Mathematical Deductions.

27. Pressure in Discharge Tube Produced by KINNERSLEY, a Spark. HARRIS, and RIESS