Willson, Robert Wheeler, 1853-1922 · Boston, New York Ginn & company · leaf 47
tripodprovided with leveling screws. If thecircle is so placed that the pointer readszero when the sight-bar is in the mag-netic meridian, then its reading whenthe sights are pointed at any star willgive the magnetic bearing of the star.It will, however, be more convenient toadjust the instrument… … Fig. 30 THE DIURKAL MOTION OF THE STARS 35 adjusted so that the circle E may be revolved without causing thelevel bubble to move. (See page 36.) A more convenient and not very expensive instrument is thealtazimuth or universal instrument shown in Fig. 31, which containssome additional parts by the…
Astronomy
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