Herschel, John F. W. (John Frederick William), Sir, 1792-1871 · London : Longman, Rees Orme · leaf 41
tsi Q R, a!(cr being more or less bent in passing throughit, the lower most, the higher less, and that which, likei> K i>, merely grazes the exterior limit of the atmosphere,not at all. Lei us consider several points, A, 13, C, D, eachmore remote tlum the last from A, and each more… … the whole reflective atmosphere PQRT. It thereforereceives twilight from the whole sky. The point B, towhich the sunhas set, receives no direct solar light, norany, direct or reflected, from all that part of its visibleatmosphere which is below A P M; but from the lenti-cular portion P R oc, which…
Astronomy
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