In the siphon recorder script dots and dashes are
represented by curves of opposite flexure. The condensers are merely
used to sharpen the action of the current, and render the signals more
concise and distinct on long cables. On short cables, say under three
hundred miles long, they are rarely, if ever, used.
The speed of signalling by the siphon recorder is of course regulated by
the length of cable through which it is worked. The instrument itself
is capable of a wide range of speed. The best operators cannot send
over thirty-five words per minute by hand, but a hundred and twenty
words or more per minute can be transmitted by an automatic sender, and
the recorder has been found on land lines and short cables to write off
the message at this incredible speed. When we consider that every word
is, on the average, composed of fifteen separate waves, we may better
appreciate the rapidity with which the siphon can move. On an ordinary
cable of about a thousand miles long, the working speed is about twenty
words per minute. On the French Atlantic it is usually about thirteen,
although as many as seventeen have sometimes been sent.
The 'duplex' system, or method of telegraphing in opposite directions at
once through the same wire, has of late years been applied, in
connection with the recorder, to all the long cables of that most
enterprising of telegraph companies--the Eastern--so that both stations
may 'speak' to each other simultaneously.
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