An elementary book on electricity and magnetism and their applications (1919)
Jackson, Dugald C. (Dugald Caleb), 1865-1951, Jackson, John Price, b. 1868, Black, Newton Henry, b. 1874 · New York, The Macmillian Co · leaf 126
n in Chapter XXII. 74. Telegraph relays. Telegraph sounders require only afraction of an ampere to operate them; but to cause thatfraction to flow through a long line, which necessarily has ahigh resistance, requires the use of a battery with a very largenumber of cells. This is undesirable because… … Samuel F. B. Morse (1791-1872J. An American artist and inventor, was born at Charlestown (now part of Boston),Massachusetts, was graduated at Yale College in 1810, and in 1832 inventedthe commercial telegraph and the dot-and-dash alphabet known by his name.In 1844 by the aid of a 830,000 grant from…
Electricity · Magnetism
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