Page:Wireless Telegraphy and Telephony (1908, Massie and Underhill).djvu/44

platinum wire within during the drawing process. The silver is then removed by immersing in nitric acid, which leaves the platinum only. Platinum wires have thus been drawn down to .00006 of an inch.

Another type, known as the Magnetic Detector, is based upon the phenomena that certain magnetic characteris-

Fig. 17.—Connections of Silicon Detector

tics in iron undergo a change under the influence of the high-frequency oscillations. This detector is illustrated in Fig. 15. It requires no local battery, but must be rotated by means of clockwork or a small electric motor. The regular telephone receiver is also used with this detector.

What is probably the simplest type of all is known as the Silicon Detector.^[1] This consists of a piece of silicon

1. Patented by Prof. G. W. Pickard.