Items related to A manual of astronomy and the use of the globes
Synopsis
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1854 Excerpt: ... be subtracted.. That is to say, when it is noon by the sun, it wants 16i minutes of it, by a well-regulated clock. It is nothing, four times during the year; namely, April 15th, June 15th, September 1st, and December 22d. The Equation of Time, is caused by the obliquity of the Ecliptic, and the variable motion of the Earth, in its orbit. What is a Bidereal day? How much longer is the solar than the sidereal day 1 What is the cause of the difference 1 What is apparent time? What is mean time? Which do clocks show 1 What is the equation of time? When is the equation of time greatest? How great is it at that time 7 When Ib it nothing? By what is it caused? In Figure 34, let E represent the Earth. ABCPQ.R. the Son's apparent orbit; A being the aphelion, and P the perihelion. Were the Sun at rest at A. the place H, on the surface of the Earth, would, as it rotates on its axis, return to the Sun in exactly the time of one rotation, and the solar day would be no longer than the sidereal day; but, during one rotation, suppose the Sun to move, apparently, from A to B; then the Earth will have to move more than one rotation, by the arc H h, in order to overtake the Sun. This causes the solar day to exceed the sidereal day, by an average difference of four minutes. But, as the Sun is not uniform in his motions, this is not always the difference. To show this, draw a circle, am no, etc., and let each of the equal arcs, am, mn, no, represent a space which the Sun would move over, during one rotation of the Earth, if he moved uniformly in a circle, and kept time with the clock. As at A, the Sun's motion is the most rapid, the divisions, as marked by the Sun, will be greater than those marked by the clock; and the place H, will arrive at m, before it reaches the Sun at B...
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- PublisherRareBooksClub.com
- Publication date2012
- ISBN 10 1130610918
- ISBN 13 9781130610918
- BindingPaperback
- LanguageEnglish
- Number of pages34
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