The signals were the short and long, or 'dots' and 'dashes' of
the Morse code. The speed of marking was so great that hand signalling
could not keep up with it, and Bain devised a plan of automatic
signalling by means of a running band of paper on which the signals of
the message were represented by holes punched through it. Obviously if
this tape were passed between the contact of a signalling key the
current would merely flow when the perforations allowed the contacts of
the key to touch. This principle was afterwards applied by Wheatstone
in the construction of his automatic sender.
The chemical telegraph was tried between Paris and Lille before a
committee of the Institute and the Legislative Assembly. The speed of
signalling attained was 282 words in fifty-two seconds, a marvellous
advance on the Morse electro-magnetic instrument, which only gave about
forty words a minute. In the hands of Edison the neglected method of
Bain was seen by Sir William Thomson in the Centennial Exhibition,
Philadelphia, recording at the rate of 1057 words in fifty-seven
seconds. In England the telegraph of Bain was used on the lines of the
old Electric Telegraph Company to a limited extent, and in America about
the year 1850 it was taken up by the energetic Mr.
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