The elements of dynamic electricity and magnetism (1903)
Atkinson, Philip. [from old catalog] · New York, D. Van Nostrand company · leaf 53
nd name of theinventor are unknown. A much earlier claim for thisinvention is made by the Chinese, but does not seem tobe well sustained. The loss of magnetic energy due to the softness ofiron seriously impaired the usefulness of the compass,but the subsequent discovery of steel furnished… … FiG. 17. tached to the under side of a circular card which ro-tates with it, the margin of which is graduated to thirty- MAGNETISM, 37 two divisions indicated by pointers, including the fourcardinal points N., S., E., W., and also to 360° where greataccuracy is required. A circular box with glass…
Electricity · Magnetism
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