Elementary lessons in electricity and magnetism (1906)
Thompson, Silvanus P. (Silvanus Phillips), 1851-1916, Schwetzky, Otto H. L. [from old catalog] · Chicago, Thompson & Thomas · leaf 451
pacebetween them one-thirtieth inch long and contain-ing a powder composed of ninety parts nickelfilings and ten parts silver filings, all coated with aninfinitely light coating of mercury. The tube issealed. A perfect vacuum is not required, but desir-able. A greater percentage of silver filings,… … 426 ELEMENTARY LESSONS ON [chap. xili. him to send signals across the Atlantic Ocean, the firstof which was sent from Poldhu, Cornwall, England,and received on Signal Hill, St. Johns, Newfoundland.It consisted in several repetitions of the three shortmarks representing the letter S in the…
Electricity · Magnetism
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