A new treatise on astronomy, and the use of globes : in two parts ... (1866)
M'Intire, James, 1799-1879 · New York : Published by A.S. Barnes & Burr ... · leaf 58
e direction F E ; hence none of that part of theatmosphere D E F above the horizon will be illuminated, andconsequently twilight will end at E. The part E I B F, thoughnot directly enlightened by the sun, receives a degree of lightby reflection from that part of the atmosphere on which heshines.… … 62 From the datum, namely, that twilight ceases when the sun is 18°below the horizo.\, find at what heiglit, by dr:iwing the diagram and work-uig the problem, the atmosphere ceases t<i reflect the suns rays. 52 ASTRONOMY. as COS. E C F 9° ar. CO 0.0053801 is to Radius 10.0000000 so is EC 3956OT…
Astronomy
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