Collins, A. Frederick (Archie Frederick), 1869- · New York, London, D. Appleton and company · leaf 50
or all time. There are several ways,though, to observe the Sun with-out danger to your eyes and asall of these are simple and costnothing you can easily try them.The most common way is to takea bit of window glass, say an inch square, and smoke one sideof it over the flame of a candle, as shown in… … Fig. 28.—Smoking Glassesover Candle Flame. so THE BOOK OF THE STARS of the Sun may be examined at length and without the leastdanger. A decided improvement over the smoked glass idea is touse a piece of red, or a piece of yellow glass, as an eyepiece, or,better, place the red and yellow glasses…
Astronomy · Stars
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