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 124
Adjusting Screws^Contact, Fig. 58. Electromagnet - Telegraph sounder. … Leg^M Leg- Fig. 59. — Telegraph key. 73. Telegraphic signals. Telegraphic signals are made upof a combination of long and short current impulses, whichare made by pressing a sending key (Fig. 59) at proper intervalsand for proper periods. A telegraph key of ordinary form ismerely a quick-acting…
Electricity · Magnetism
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