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 59
yaimed and kept in position. To make a heliograph, get a board 12 inches long, 4 incheswide and 1 inch thick and cut a piece out of one end 4 inches ^ftnri Fig. 40.—Base for Heliograph. long and 1 inch wide, as shown in Fig. 40. Bore a ^-inchhole through the slotted end and another 14-inch hole 4%… … HOLE stick fasten a mir-ror about 4 inchessquare. This mirrorshould be perfectlysmooth—a plateglass mirror is thebest — and have ahole yi6 inch in di-ameter drilledthrough the centerof the mirror forsighting the heliograph, as shown in Fig. 41. Any optician willdrill the hole for you for a quarter…
Astronomy · Stars
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