Anonymous
Published: 2013-09
Total Pages: 36
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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1859 edition. Excerpt: ...multiplied by 3, gives 2'58o for the variation in 3 hours, and this being added (because the equation is increasing) to o, m 59" 10, the equation of time at apparent noon, the result w iom 68, to be added (according to the precept at the head of the column) to the given apparent time 6h, whence we obtain 6h iom i' 68 for the mean time required. At page I. of the month of April, we observe, at the head of the column subt'f'onii W'c signifies that a change of precept occurs in the course of the month; and between the equations opposite to the 15th and 16th days of the month, a black line, indicating that the change occurs between the apparent noons of those days. The upper precept applies to all the quantities above the black line; and the lower precept to all the quantities below it: that is, in the instance referred to, the equation of time is to be added to apparent time from the 1st of April to the instant at which the equation becomes om o', which happens between the noons of the 15th and 16th days of the month; but after that instant the equation is to be subtracted from apparent to obtain mean time. Page II. of each Month. The Sun's Apparent Sight Ascension and Declination at mean noon have been deduced from its apparent Longitude and Latitude given at page III., and the apparent obliquity of the ecliptic at page 242. They denote the apparent position of the true Sun with reference to the equator, and the true equinox, at the instant the Greenwich mean time clock, or chronometer, indicates oh om o, or when the hour angle of the true Sun is equal to the equation of time. To find the Right Ascension and Declination for any other mean time and place, as at 9h 20m A.M. March 2, 1863, in longitude 980, or 61' 32%...