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POPULAR SCIENCE MONTHLY. 



immensely improved this arrangement, as described by him in a lec- 

 ture given before the Society of Arts, on May 17, 1901, by syntonizing 

 the two circuits and making the circuit, consisting of the capacity of 

 the aerial and the inductance of the secondary circuit of the oscillation 

 transformer, have the same time-period as the circuit consisting of the 

 Leyden jars, or energy-storing condenser, and the primary circuit of 

 the oscillation transformer, and by so doing immensely added to the 

 power and range of the apparatus. 



Starting from these inventions of Braun and Marconi, the author 

 devised a double transmission system in which the oscillations are 

 twice transformed before being generated in the aerial, each time with 

 a multiplication of electromotive force, and a multiplication- of the 

 number of groups of oscillations per second. This arrangement can 

 best be understood from the diagram (see Fig. 15). 



Fig. 15. Alternating Current Double Transformation Power Plant for Generating 

 Electric Waves (Fleming), a, alternator; H^H^, choking coil; A', signaling key; 7', step-up 

 transformer; S-^S^, spark gap; CjCo, condensers; Ti7\, oscillation transformers; ^4, aerial; 

 E, earth plate. 



In this case, a transformer T or transformers, receive alternating 

 low frequency current from an alternator a, being regulated by passing 

 through two variable choking coils, H^ and Hn, so as to control it. This 

 alternating current is transformed up from a potential of two thousand 

 to twenty, forty or a hundred thousand, and is employed to charge a 

 large condenser C^, which discharges across a primary spark gap S^ 

 through the primary coil of an oscillation transformer T^. The sec- 

 ondary circuit of the oscillation transformer is connected to a second 

 pair of spark balls 8^, which in turn are connected by a secondary con- 

 denser C2, and the primary circuit of a third transformer To, and the 

 secondary circuit of this last transformer are inserted between a Marconi 

 aerial A and the earth E. WTien all these circuits are tuned to reso- 

 nance by Mr. Marconi's methods, we have an enormously powerful 

 arrangement for creating electric waves, or rather trains of electric 

 waves, sent out from the aerial, and the oscillations are controlled and 

 the signals made by short-circuting one of the choking coils. 



Another transmitting arrangement, which involves a slightly dif- 

 ferent principle, and employs no oscillation transformer, is one duo 



