A supplement to Ures Dictionary of Arts, Manufactures, and Mines, : containing a clear exposition of their principles and practice. . dle moves to the right, and viceversa. An alphabet is constructed fromthe combination of these two elementarymotions, one or more of either or bothkinds ol deflection being used for the va-rious letters, as sliown on the engraveddial. 1 lis is Cooke and Wheatstones sin-gle needle instrument. Jiff. 269. The form and cliaracter of their doubleneedle instrument is shown in fiq 270 ItIS precisely a duplicate of the former ; twohandles, and their respective springs,
A supplement to Ures Dictionary of Arts, Manufactures, and Mines, : containing a clear exposition of their principles and practice. . dle moves to the right, and viceversa. An alphabet is constructed fromthe combination of these two elementarymotions, one or more of either or bothkinds ol deflection being used for the va-rious letters, as sliown on the engraveddial. 1 lis is Cooke and Wheatstones sin-gle needle instrument. Jiff. 269. The form and cliaracter of their doubleneedle instrument is shown in fiq 270 ItIS precisely a duplicate of the former ; twohandles, and their respective springs, studsand cylinders, two multipliers, and twomagnetized needles, with their external in-dexes and two telegraph wires. One bat-tery, however, is sufficient. One or moreof either or both kinds of deflection ofeitlier or both needles, accordiii- to thecode engraved on the dial, constitutes thealphabet. This instrument is very exten-sively emjiloyed; messages are sent by itwitli extreme rapidity. Another property possessed by a wireconveying a current, is that of converting we have a dial anddescribed, capable of an index,being de-. ELECTEO-TELEGRAPHY. 503 soft iron, for the time, into a magnet. Tiie attractive power, which can thus be given to,and withdrawn from, the soft iron at pleasure, is turned to useful account, either in produc-ing direct mechanical action, or in liberating the detents of a clock movement. Here alsothe effect of the solitary wire is inappreciable, and many convolutions around the iron arenecessary in order to obtain a useful result. The simplest application of this principle is shown in Jig. 271. Here are two brassreels, filled with cotton-covered copper wire, in one length. They are hollow, and a U-sliaped bar of iron passes through them, presenting its ends at the - ^ face turned toward us in the draw-in,. This bar becomes magnetic— forms what is called an electro-magnet—every time and as longas an electrical current circulatesin the wire; and its end
Size: 1322px × 1890px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1860, bookpublishernewyo, bookyear1864
