The main principle of his type-printer was the printing of each letter
by a single current; the Morse instrument, then the principal receiver
in America, required, on the other hand, an average of three currents
for each signal. In order to carry out this principle it was necessary
that the sending and receiving apparatus should keep in strict time
with each other, or be synchronous in action; and to effect this was the
prime difficulty which Professor Hughes had to overcome in his work. In
estimating the Hughes' type-printer as an invention we must not forget
the state of science at that early period. He had to devise his own
governors for the synchronous mechanism, and here his knowledge of
acoustics helped him. Centrifugal governors and pendulums would not do,
and he tried vibrators, such as piano-strings and tuning-forks. He at
last found what he wanted in two darning needles, borrowed from an old
lady in the house where he lived. These steel rods fixed at one end
vibrated with equal periods, and could be utilised in such a way that
the printing wheel could be corrected into absolute synchronism by each
signal current.
In 1854, Professor Hughes went to Louisville to superintend the making
of his first instrument; but it was unprotected by a patent in the
United States until 1855.
Pages:
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315