File:Guy's Elements of astronomy - and an abridgment of Keith's New treastise on the use of the globes (1864) (14778645551).jpg

Identifier: guyselementsofa00guyj (find matches)
Title: Guy's Elements of astronomy : and an abridgment of Keith's New treastise on the use of the globes
Year: 1864 (1860s)
Authors: Guy, Joseph, 1784-1867 Keith, Thomas, 1759-1824. A new treatise on the use of the globes
Subjects: Astronomy
Publisher: Philadelphia, C. Desilver
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

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rbit in which the moon really moves (as was noticed under the articleEclipses) is different from the ecliptic; one half being elevated 5i de-grees above it, and the other half as much depressed below it. Andthis oblique motion causes some small difference in the time of herrising and setting from what has been above mentioned. At the polar circles, the full moon neither rises insummer, nor sets in winter. For the winter full moonbeing as high in the ecliptic as the summer sun, shemust therefore continue, while passing through thenorthern signs, above the horizon ; and the summerfull mooji being as low in the ecliptic as the winter sun,can no more rise, when passing through the southernsigns, than he does. CHAPTER XXXIV. OF LEAP-YEAR. The time our earth takes to make one complete revolution, in its orbit round the sun, we call a year. Tocomplete this with great exactness is a work of consi-derable difficulty. It has mostly been divided intotwelve iHonths of 30 days. Pru^t^ .91 /y-/////
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LEAP-YE AK. 93 t Tlie ancient Heorew monuio jonsisled of 30 days each, except thelast, which contained 35. Thus the year contained 3l5 daws. An in-tercakry month at the end of 120 years supphed the ditlereiu e. The Athenian months consisted of 30 and 29 days alteriiaiely, ao-cording to the regulation of Solon. This calculation produced a yearof 354 days, and a little more than one-third. But as a soiur montkcontains 30 days, 10 hours, 29 minutes, Melon, to reconcile the differfence between the solar and lunar year, added several embolismiCt orintercalary months, during a cycle, or revolution of 19 years. The Roman months, in the time of Romulus, were only ten of 30and 31 days. Numa Pompilius, sensible of the great deficiency of thiscompulation, added two more months, and made a year of 355 days. The Egyptians had fixed the length of their year to 365 days. Julius Caesar, who was well acquainted with thelearning of the Egyptians, was the first who attained toany accuracy on the subject

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