Collins, A. Frederick (Archie Frederick), 1869- · New York, London, D. Appleton and company · leaf 63
ved, set the mirror so that the reflected beam ofsunlight shines directly on the place. To send signals in the 48 THE BOOK OF THE STARS Morse code all you need to do to make dots and dashes is toplace a sheet of cardboard before the mirror and take it away;the length of time the mirror remains… … Fig. 44.—Heliograph Complete. easy matter, for the spaces marking the hours on the dial arenot equal as they are on the face of the clock and this will makeit hard to figure out. A kind of sundial that will give the correct Sun time though,can be easily made and at little cost. Get a strip of tin…
Astronomy · Stars
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