A popular handbook and atlas of astronomy, designed as a complete guide to a knowledge of the heavenly bodies and as an aid to those possessing telescopes (1891)
Peck, William, Sir, 1862-1925 · New York, G. P. Putnam's Sons · leaf 175
conis. ^, Urs.e ^Iajoris. Another very good test for instrumental defects is a star of the second magnitude, as any imperfection isrevealed by the stars disc being surrounded with numerous rays. If these are equally distributed round thecentral disc, the fault belongs to the object-glass, and… … Though it may not at first seem so, a suitable stand is of the greatest importance, for it not unfrequentlyhappens that by means of a defective stand, a good instrument is rendered nearly useless. Stability ofstructure is the first consideration that should be given in the choice of an instrument;…
Astronomy
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