Star-land : being talks with young people about the wonders of the heavens (1891)
Ball, Robert S. (Robert Stawell), Sir, 1840-1913 · London ; Paris : Cassell & Co. · leaf 18
will ask, how do we learn all this ? for as nobodycould ever make such a journey, how can w7e feel certainthat the sun is so excessively hot 1 I know that what I say istrue for various reasons, but I will only mention one, which The Sun. 3 is derived from an experiment with the burning-glass,… … Fig. 1.—How to use the Burning-glass. are. On a fine sunny day in summer, you turn the burning-glass to the sun, and by holding a piece of paper at the properdistance a bright spot will be obtained (Fig. 1). At thatspot there is intense heat, by which a match can be lighted,gunpowder exploded, or…
Astronomy
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