Project Gutenberg #54475
Discoveries and Inventions of the Nineteenth Century
Robert Routledge
1900Routledge's illustrated survey of nineteenth-century engineering and invention, prepared chapter by chapter from Project Gutenberg HTML.
Project Gutenberg #54475 Public domain in the United States Cover source Local typographic cover created for MojiMori from public-domain source metadata
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irregular motions of the spot of light can be interpreted by a skilled clerk, who, by long experience, recognizes, in quite dissimilar effects, the same signal sent by the clerk at the other end in precisely the same way. Thus a first contact, corresponding with a dot of the Morse alphabet, may cause the light to move some distance on the scale, a second contact immediately succeeding moves it but a little way farther, and a third may occasion a movement hardly perceptible.
The messages sent by the mirror galvanometer must be read as they are received; and, as a telegraphic instrument, it is wanting in the manifest advantages attending a recording instrument. Sir W. Thomson has, however, devised another receiving instrument of great delicacy, which is termed the syphon recorder. We cannot here describe its admirable mechanical 572and electrical details, but the chief feature is that the attractions and repulsions of the currents are made to produce oscillations in a syphon formed of an extremely fine glass tube, the shorter branch of which dips in a trough of ink, and the longer branch terminates opposite to, but not touching, a band of paper, which is continuously and regularly drawn along by clockwork while the message is being received. The tube is a mere hair-like hollow filament of glass, and the ink, which would not itself flow from a tube of so fine a bore, is squirted out by electrical repulsion when the insulated reservoir in which it is contained is electrified at the receiving station by an ordinary machine. The message as written by this instrument appears thus:
The reader, on comparing these signals with the Morse code on page 560, will have no difficulty in discovering their relation to it.