Theory and practice of the electric telegraph; a manual for operators and students (1875)
Churchill, Charles Henry, d. 1904. [from old catalog] · Oberlin, Ohio, Sherman & bros. · leaf 157
distant is enough to cause a visible deflection of the needleSuch a bundle is called a thermopile and is one of the most 136 MANUAL OF TELEGRAPHY. … sensitive forms of thermometer ever devised. Any currentof heated air excites electric action. I. The Automatic Telegraph.—The object of this inven-Flg- 62- tion is co enable any number of operatorsto receive messagesfrom customers andby a certain arrange-ment to send allthese by one…
Telegraph
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