File:The Americana; a universal reference library, comprising the arts and sciences, literature, history, biography, geography, commerce, etc., of the world (1908) (14597999809).jpg

Identifier: americanaunivers03newy (find matches)
Title: The Americana; a universal reference library, comprising the arts and sciences, literature, history, biography, geography, commerce, etc., of the world
Year: 1908 (1900s)
Authors:
Subjects: Encyclopedias and dictionaries
Publisher: New York : Scientific American Compiling Dept.
Contributing Library: University of California Libraries
Digitizing Sponsor: Internet Archive

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ly, when heavier cableswere laid, the speed was increased to as muchas 20 words a minute. The Siphon Recorder.— In 1870 Lord Kel-vin perfected his siphon recorder for workinglong cables, and it at once supplanted the mirrorinstrument, as it worked just as well with fee-ble currents, gave a written record of signalsreceived, and enabled one man to do the workof two. An exceedingly light coil of fine wire(in shape and size like the long, narrow Owhich would be obtained by winding severalhundred turns of fine silk thread around thepalm of the open hand) is delicately suspendedbetween the two poles of a powerful magnet.As the electric signals from the cable flowthrough the coil of wire, it swings round underthe influence of the magnet, back or forwardaccording as the current is positive or negative.The motions of the coil are transmitted by silkenfibres to a little glass siphon about as thick as aneedle and three or four inches long, suspendedso as to swing with perfect freedom. One end
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CABLES of the siphon dips into a pot of ink, and theother end hangs close above a moving strip ofpaper. The signals are so feeble that if theend of the glass siphon rested on the paper itwould not move at all, but by causing the siphonto vibrate continuously against the paper thefree motion of the siphon is not interferedwith, and the ink is spluttered upon the paperso that the siphon traces a line of very fine dotsand thus records the signals transmitted throughthe cable. This instrument, though crude atfirst, has gradually been perfected. It is nowthe most important part of modem cable appa-ratus. The Duplex System.— The next improve-ment, undoubtedly the greatest ever made forincreasing speed, was the invention of a success-ful system of duplexing cables by Dr. Alexan-der Muirhead and Herbert Taylor in 1875.This invention rendered it possible simultane-ousl)- to send messages both ways through along ocean cable. In 1878 the Direct UnitedStates cable across the Atlantic was succes

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