Collins, A. Frederick (Archie Frederick), 1869- · New York, London, D. Appleton and company · leaf 59
d eitherby day or by night.A simple and effective way to signal in the daytime whenthe Sun is shining is by using a mirror, that is, a looking-glass,as it is commonly called. Every boy knows how to make flasheswith a mirror, so it will be enough to say here that the glassis held in the hand in such… … Fig. 37. uA -Boy Focusing Burning Glass onLeaves to Make Fire. THE SUN, BRIGHTEST OF ALL STARS 39
Astronomy · Stars
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