A short course in astronomy and the use of the globes (1871)
Kiddle, Henry, 1824-1891 · New York, Chicago, Ivison, Blakeman, Taylor & co. · leaf 36
cessation of twilight, wecan calculate the extent or height of the atmosphere. 38. If the circles of daily motion were at all placesequally inclined to the horizon, the duration of twilightwould everywhere be the same; since the earth wouldalways have to turnthe same amount tobring the sun 18°… … DURATION OF TWILIGHT. 37. WThen does twilight cease ? Eemark ? 3S. Why does the duration of twilightvary ? Illustrate by the diagram. 5 n REASONS. e the earth in the centre; P II the altitude of the pole in oneposition of the sphere, and P H its altitude in one less oblique;E E and E E the…
Astronomy
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