The book of stars; being a simple explanation of the stars and their uses to boy life, written to conform to the tests of the Boy scouts (1915)
Collins, A. Frederick (Archie Frederick), 1869- · New York, D. Appleton and company · leaf 152
inal direction, or refracted. A convex lens, see Fig. 146, is a lens which is thicker inthe middle than it is at the edges. A convex lens is used formagnifying an object; or forforming an image so that itcan be magnified by anotherlens as in a telescope, for form-ing an image on the screenof a… … 134 THE BOOK OF THE STARS holding a sheet of paper, or the hand under the lens and lettingthe sunlight pass through it; where the spot of light is smallest
Astronomy · Stars
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