WIRELESS TELEGRAPHY. 



61 



spond to each other if they are made sufficiently large, if they 

 are properly placed, and if a powerful current is used to excite 

 one coil. Thus, by simply varying tlie distance between the coils 

 of wire we can send messages through the air between stations 

 which are not connected with a wire. This method, however, 

 does not constitute the system of wireless telegraphy of Mar- 

 coni, which it is the object of this paper to describe. Marconi has 

 succeeded in transmitting messages over forty miles between points 

 not connected by wires, and he has accomplished this feat by merely 

 slightly modifying the disposition of the coils, thus revealing a 

 new possibility of the wondrous transformer. If the reader will 

 compare the following diagram (Fig. 2) with the photograph (Fig. 

 1), he will see how simple the sending apparatus of Marconi is. 



S is a gap between the ends of one coil, across which an elec- 

 tric spark is produced whenever the current from the batteries 

 B flowing through the coil C is broken by an arrangement at D. 

 This break produces an electrical pulsation in the coil C, which 

 travels up and dow^n the wire W, which is elevated to a consid- 

 erable height above the ground. This pulsation can not be seen 

 by the eye. The wire does not move; it appears perfectly qui- 



w 



Fig. 2. — Diagram of the arranorement of wires and batteries at tlie receiving station. 



escent and dead, and seems oul}^ a wire and nothing more. At 

 night, under favorable circumstances, one could see a luminosity 

 on the wire, especially at the end, when messages are being trans- 

 mitted, by a powerful battery B. 



It is very easy to detect the electric lines which radiate from 



