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 160
value. He was one of the first to appreciate the principle of Con-servation of Energy. NATURE AND PROPERTIES OF MAGNETISM 133 rate magnetic survey of the important portions of the earthssurface. 100. A ships compass. The form of ships compass whichis now quite generally used was introduced by Lord… … Fig. 81. — Kelvins compass card. of lightness. In this middle area six magnets are slung on to radialthreads, as shown in figure 81. In this way the oscillations of themagnets are small and are quickly damped out. In some formsthe card is floated on liquid, which takes most of the weightoff the…
Electricity · Magnetism
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