In the bend of this wire and the V-shaped groove filed
into the carbon, lay a needle. This will complete the receiving
station. Use a spark coil in connection with a telegraph key for
the sending station, making a ground with one wire, and have the
other connected with another aerial line.
By connecting the telephone receiver to the cell and at the same
time having a short circuit a receiving station is made. As the
telephone offers a high resistance, part of the current will try
to take the shorter high resistance through the needle. If the
waves strike across the needle, the resistance is less, and thus
less current travels through the telephone receiver. If the wave
ceases, the resistance between the needle and the carbon is
increased, and as less current will flow the short way, it is
compelled to take the longer metallic way through the windings of
the receiver, which will cause the clickings that can be heard.
** To Preserve Putty [121]
Putty, when left exposed to the air, will soon become dry and
useless. I have kept putty in good condition for more than a year
by placing it in a glass jar and keeping it entirely covered with
water.
Pages:
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301