Recreations in astronomy : with directions for practical experiments and telescopic work (1879)
Warren, Henry White, 1831-1912 · New York : Harper & Brothers · leaf 53
a room and admit a beamlight through the key-hole,that light goes in straighthouses and trees in rows,tronomer projects straight e of 20 is 400, of 40 is 1000. Divide 1600 byone light is four times as bright as the other,irected, and bent, as well as iron bare. ]darkenof sunlight through a shutter,… … )iffusiou of Light ter, a piece of glass coated on one side with black varnish, and you cansend your ray anywhere. By using two mirrors, or having an assistantand using several, you can cause a ray of light to turn as many cornersas you please. I once saw Mr. Tyndall send a ray into a glass jar…
Astronomy
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