A text-book of general astronomy : for colleges and scientific schools (1888)
Young, Charles A. (Charles Augustus), 1834-1908 · Boston ; London : Ginn & Company · leaf 65
rthe screw. The box containingthese wires, and carrying the eye-piece and screw, can itself beturned around in a plane perpendicular to the optical axis of thetelescope, and set in any desired position ; for example, so that themovable wires shall be parallel to the celestial equator, while the … Fig. 28. — The Filar Position-Micrometer.
Astronomy
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