Over these coils are wound long, fine wire coils. F, and in the same direction thronahout as the coils, E. These coils are secondaries in which currents of very high potential are induced. Mr. Tesla, as a rule, connects all the coils, F, in one series, and all the second aries, F, in another. On the intermediate poles. B, are wound fine wire energizing coils, G, which are connected in series with one an other, and also with the series of secondary coils, F, the direction of winding being such that a current impulse induced from the primary coils, B, imparts the same magnetism to the poles B as that produced in poles A by the primary impulse. This condition is indicated by the letters .ir S'. In the circuit formed by the two sets of coils, F and G, is introduced a condenser, H, the circuit being otherwise closed upon itself, while the free ends of the circuit of coils, E, are connected to a source of alter nating currents. As the condenser capacity which is needed in any particular motor of this kind is dependent upon the rate of alternation or the potential, or both, its size, and hence its cost, as before explained, may be brought within economical limits for use with the ordinary circuits. It is
evident that by giving to the condenser proper value, any desired difference of phase between the primary and secondary energizing circuits may be obtained.
Motors embodying the above principles have also been constructed by Hutin and Leblanc, of France.
[For more detailed descriptions of electric motors, the reader is referred to the following works and papers : The Electric Motor and its Applications. Martin & Wetzler ; Dynamo Electric Machinery, S. P. Thompson : Electric Transmission of Energy. Kapp ; Electricity as a Afotirc Power, Du Moneel ; also various papers by Kapp, Esson, 3lorcley, and others in the Transactions of the London Institution of Electrical Engineers, and papers in the Trans actions of the American Institute of Electrical Engineers. Also the following periodicals : The Electrical Engineer, The Electrical World, Electrician. Electrical Review, La Lumiere Electrigue. l'Electricien.. See also the index to periodical electrical literature, Fortschritte der Elek,trotechnik, Berlina