Astronomy for schools; upon the basis of Mons. Arago's lectures at the Royal observatory of Paris .. (1841)
Arago, F. (François), 1786-1853, Haskins, Roswell William, [from old catalog] ed · New York, Robinson, Pratt & co.; · leaf 270
y enjoy until the sun has descended 18° be-low the horizon, the moon, during this long absenceof the sun, dispenses its light to them. We shouldadd, also, that the twilight must be more intense thanelsewhere, by reason of the rapid increase of the den-sity of the air, at moderate heights, in… … Finally, at the polar circles, fig. 49, the zenith verynearly coincides with the tropick. When, therefore,the sun, S, is in the planeof the equator and de-scribes the circle S E,which is divided by the ho-rizon, S A, into two equalparts, the days and nightswill be of equal length.But when it…
Astronomy
Internet Archive · Library of Congress · Public Domain Mark 1.0. Free to use for anything.
