[ 312 ] 



XXX. A Quantitative Study of the High- Frequency Induction- 

 Coil. By W. P. Boynton*. 



THE behaviour of circuits containing self- and mutual- 

 induction, and some of the properties of the disruptive 

 discharge of a leyden-jar, were experimentally investigated 

 by Faraday | and Joseph Henry + . The latter, besides 

 studying the action of two mutually inducing coils, one 

 of which was traversed by the current from a galvanic 

 battery, also discharged a leyden-jar through one coil 

 and noted the currents induced in the neighbouring coil §. 

 Henry also noted phenomena in the discharge of the Leyden 

 jar from which he concluded that this must be oscillatory in 

 character ||. 



Perhaps the first direct experimental verification of the 

 oscillatory character of this discharge was made by Feddersen 

 in the years 1857-62 ■**, by observing the spark in a revolving 

 mirror. 



The mathematical theory of the oscillatory discharge was 

 given by Lord Kelvin tt and Kirchhoff % \. The general theory 

 of electrical oscillations has been discussed at more or less 

 length, particularly by J. J. Thomson §§. 



Hittorf mi, J. J. Thomson 1H[, and others have used the 

 discharge of a leyden-jar through a coil of wire about a 

 vacuum tube as a means of studying the behaviour of 

 the rarefied gas. Within- the present decade many have 

 repeated Henry's experiment of discharging a condenser 

 through one coil of wire and studying the effect produced 

 in a secondary circuit. Many"**"* have paid particular attention 



* Communicated by Prof. A. G. Webster. 



t Experimental Researches : Series I. Induction of Electric Currents ; 

 Series XII. The Disruptive Discharge. 



X Smithsonian Miscellaneous Collections — Scientific Writings of 

 Joseph Henry : Contributions to Electricity and Magnetism, iii. (1838) 

 p. 108, & iv. (1840), "On Electromagnetic Induction;" v. (1842) p. 200, 

 " On Electrostatic Induction and the Oscillatory Discharge." 



§ Ibid. pp. 132 et seq. || Ibid. p. 200. 



** Pogg. Ann. ciii. p. 69 (1858), eviii. p. 497 (1859), cxii. p. 452 

 (1861), cxiii. p. 437 (1861), cxvi. p. 132 (1862). 



if Phil. Mag. (4) v. p. 393 (1853) ; Math, and Phys. Papers, vol. i. 

 p. 540. 



XX Pogg. Ann. cxxi. p._ 551 (1864) ; Ges. Abh. p. 168. 



§§ Recent Researches in Electricity and Magnetism, chap. iv. p. 251. 



I||| Wied. Ann. xxi. p. 90 (1864). 

 , Iffi Proc. Roy. Soc. xlv. p. 269 (1869) ; Recent Researches, p. 92. 



*** Nikola Tesla, Electrical Engineer (N.Y.), xii. p. 35 (1891), xv. 

 pp. 42, 65, 88, 531, 553, 579, 603, 626 (1893) ; published also in book 

 form. Elihu Thomson, Elec. Eng. xiii. pp. 159, 199 (1892). H. Ebert, 

 Wied. Ann. liii. p. 144 (1894). Elster, 10. Jakresber. des Ver.f. Naturiv. 

 zu Braunschweig, p. 43 (1895) ; Wied. Beibl xx. p. 338 (1896). 



