Astronomy for the use of schools and academies (1882)
Gillet, J. A. (Joseph Anthony), 1837-1908, Rolfe, W. J. (William James), 1827-1910 · New York : Potter, Ainsworth, & Co. · leaf 201
s surface is reduced by clouds or 182 ASTRONOMY. nearness to the horizon, or by the use of colored glass.During the years 1871 and 1872 spots were visible to thenaked eye for a considerable portion of the time. Thelargest spot yet recorded was observed in 1858. It had abreadth of more than a… … Professor Langley, and drawn on the same scale as the smallcircle in the upper left-hand corner, which represents thesurface of half of our globe. 181. The Penumbral Filaments. — Not unfrequently thepenumbral filaments are curved spirally, indicating a cyclonicaction, as shown in Fig. 195. In such…
Astronomy
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