This print is composed of long shaded lines,
some parts light, others dark, giving the effect of a picture, you
understand?"
"Yes, yes," I exclaimed, thoroughly excited.
"Well, he resumed as the print widened visibly, this tinfoil negative
is wrapped around a cylinder at the other end of the line and a
stylus with a very delicate, sensitive point begins passing over it,
crossing the parallel lines at right angles, like the other lines
of a regular halftone. Whenever the point of the stylus passes over
one of the lighter spots on the photographic print it sends on a
longer electrical vibration, over the darker spots a shorter
vibration. The ever changing electrical current passes up through
the stylus, vibrates with ever varying degrees of intensity over
the thousand miles of telephone wire between Chicago and this
instrument here at the other end of the line.
"In this receiving apparatus the current causes another stylus to
pass over a sheet of sensitised chemical paper such as we have here.
The receiving stylus passes over the paper here synchronously with
the transmitting stylus in Chicago. The impression which each
stroke of the receiving stylus makes on the paper is black or light,
according to the length of the very quickly changing vibrations of
the electric current.
Pages:
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296