Olmsted, Denison, 1791-1859. [from old catalog] · New York, R. B. Collins · leaf 87
.But during the 27^ days inwhich the spot has been per-forming its apparent revolution,the earth has been advancingin his orbit from E to E, wherethe visible disk of the sun is AB. Consequently, before the spot can appear againon the limb from which it set out, it must describe somuch more than an… … 107. A telescope of moderate powers is sufficient toshow the spots on the sun, and it is earnestly recom-mended to the learner to avail himself of the first oppor- 107. How large a telescope is sufficient to view the spots onthe sun ? How is the eye protected from the glare of the sunslight ? How…
Astronomy
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