American telegraphy and encyclopedia of the telegraph; systems, apparatus, operation (1909)
Maver, William, jr. [from old catalog] · New York, Maver publishing company · leaf 154
mall telescope t focused upon thamirror 711, Fig. loia, the scale appear-ing to move past the hair mark on themirror, the light from a lamp or windowbeing thrown on the scale. This gal-vanometer is not, as a rule, as sensitive as the Kelvin galvanometer, but is notreadily affected by external… … 20 AMERICAN TELEGRAPHY. AOLTMETERS, AMMETERS. Voltmeters and ammeters are now extensively used for measuring voltage andcurrent strength respectively, and for line tests. These instruments have the ad-vantage that in measurements of E. M. f. and current strength the results are givenupon a scale…
Telegraph
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