. Bulletin. Science. Figure 22.—Wheatstone and Cooke's single-needle, double- needle, and 5-needle telegraphs (left to right). From E. Feyerabend, Der Telegraph von Gauss und Jl'eber, Berlin, 1933. P- 75- Mechanization of the process of telegraphy brought about the instrument that eventually came to domi- nate those English telegraph lines where traffic was heavy. In the dial and the needle telegraph systems the speed of transmission depended on the rapidity with which the transmitter could be worked manually; further progress was made by re- placing the manual key with Bain's paper tape. With
. Bulletin. Science. Figure 22.—Wheatstone and Cooke's single-needle, double- needle, and 5-needle telegraphs (left to right). From E. Feyerabend, Der Telegraph von Gauss und Jl'eber, Berlin, 1933. P- 75- Mechanization of the process of telegraphy brought about the instrument that eventually came to domi- nate those English telegraph lines where traffic was heavy. In the dial and the needle telegraph systems the speed of transmission depended on the rapidity with which the transmitter could be worked manually; further progress was made by re- placing the manual key with Bain's paper tape. With Wheatstone's "automatic fast speed printing instru- ment" (fig. 28) of 1858 (British patent 1239, June 2, 1858), the operator first used a manual perforator to punch holes in a stiff paper tape which was then sent through a transmitter that was operated by this tape. The receiver recorded the message produced by this transmitter directly in the form of dots and dashes. Later the Wheatstone receiver produced punched tape similar to that used in the transmitter, and this tape was used to operate a printing machine. Depending upon the circuit, from 50 to 150 words per minute could be sent by this method, which was used in most English telegraph systems carrying heavy traffic during the 19th century. Across the ocean in the New World, inventors were also seeking to apply electricity to communi- cation devices. The first inventor actually to devise and set up an electric telegraph in the United States was Harrison G. Dyar.^" Sometime between 1826 and 1828 Dyar worked out an electrochemical system whereby messages were recorded by sparks passing through treated paper and discoloring it. The dot and dash pattern formed by the discolorations indicated the message. Dyar's telegraph was tried out near a race track on Long Island by setting up poles with insulators to carry the wire that formed half the circuit and using the earth as a ground return for the other half. H
Size: 2109px × 1185px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorunitedstatesdepto, bookcentury1900, booksubjectscience
