MULTIPLEX TELEPHONY AND TELEGRAPHY—SQUIER. 135 
Electric waves of ultra sound frequencies are guided by means of 
wires of an existing commercial installation and are made the vehicle 
for the transmission of additional telephonic and telegraphic messages. 
APPARATUS AND EQUIPMENT. 
Under a special appropriation granted to the Signal Corps by Con- 
gress in the army appropriation act of 1909, a small research labora- 
tory has been established at the Bureau of Standards, in the suburbs 
of the city of Washington. This laboratory is equipped with the 
latest forms of apparatus now employed in the wireless telephone and 
telegraph art, and also with the standard types of telephone and 
telegraph apparatus now used upon wire circuits. The small con- 
struction laboratory of the United States Signal Corps is located at 
1710 Pennsylvanue Avenue and is also equipped with the usual types 
and forms of apparatus used in transmitting intelligence by electrical 
means. Hach of these laboratories is supplied with a wireless tele- 
phone and telegraph installation with suitable antenne. In addi- 
tion, these two laboratories are connected by a standard telephone 
cable line about 7 miles in length, which was employed in the experi- 
ments described below. 
THE 100,000-CYCLE GENERATOR.! 
The high-frequency alternator, ‘which is shown complete with 
driving motor and switchboard in the accompanying illustrations, is 
a special form of the inductor type designed for a frequency of 100,000 
cycles with an output of 2 kilowatts, making it adapted for use in 
wireless telephony or telegraphy (pl. 1). : 
Driving motor—The motor is a shunt-wound 10-horsepower ma- 
chine with a normal speed of 1,250 revolutions per minute. It is 
connected by a chain drive to an intermediate shaft which runs at a 
speed of 2,000 revolutions per minute. The intermediate shaft 
drives the flexible shaft of the alternator through a De Laval turbine 
gearing, having a ratio of 10 to 1. The flexible shaft and inductor 
thus revolve at a speed of 20,000 revolutions per minute. 
Field coils —The field coils, mounted on the stationary iron frame 
of the alternator, surround the periphery of the inductor. The 
magnetic flux produced by these coils passes through the laminated 
armature and armature coils, the air gap, and the inductor. This 
flux is periodically decreased by the nonmagnetic sections of phos- 
phor-bronze embedded radially in the inductor at its periphery. 
Armature coils—The armature or stators are ring-shaped and are 
made of laminated iron. Six hundred slots are cut on the radial 
face of each; a quadruple silk-covered copper wire, 0.016 inch (0.4 
_— 
1 Alexanderson, Trans. Amer. Inst. Electr. Eng., vol. 28, p. 399, 1909. 
