Duff, A. Wilmer (Alexander Wilmer), b. 1864, ed, Guthe, Karl Eugen, 1866-1915, Hallock, William, 1857-1913, Lewis, E. Percival (Exum Percival), 1863-1925, Goodspeed, Arthur W. (Arthur Willis), b. 1860, Carman, Albert Pruden, b. 1861, McClung, Robert Kenning, 1874- · Philadelphia, P. Blakiston's Son & Co · leaf 513
494 ELECTRICITY AND MAGNETISM. Lines of equal declination have the same general arrangementas the geographical meridians and are called isogonic lines. Theyevidently converge at the magnetic poles. The isogonic of zerodeclination is knowTi as an agonic line. Fig. 358 shows the isogoniclines for the… … Fig. 359. the Coast and Geodetic Survey. Each of these lines is drawnfrom observations at stations many miles apart and hence giveonly the general course of the true curves. When the curves aredrawn from obser^-ations at stations close together they are foundto be much more irregular. This is well…
Physics
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