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 160
is adouble concave lens 1 inch in diameter andhaving a focus of 6 inches. This lens canbe had for about 40 cents. Cut a strip of thin, tough cardboard % inch wide and 6inches long; on this strip glue a strip of heavy pasteboard %inch wide and 5% inches long, and have one end of both pieceseven, as… … Fig. 155.—Opera Glass Telescope. Cross Section. heavy pasteboard by slicing out a very thin strip with the pointof a sharp knife, being careful not to cut through the thin card-board. Now bend the strips around the lens with the lens inthe groove, glue over the thin end as shown in Fig. 154, and…
Astronomy · Stars
Internet Archive · Library of Congress · Public Domain Mark 1.0. Free to use for anything.
