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A Table shewing the Time of the Sun, Moon, and Stars' Setting, when they have North Declination, or the
To find the Time of the Sun's Rising, Setting, and Length of the Day and Night, by this Table. -
First. Find the Sun's Declination at the Top of the Page (marked with the Degrees of Declination) and the Latitude in the Right, or Left Hand Columns (marked Lat.) and in the common Angle of Meeting is the Time of Sun Setting, if the Sun has North Declination, but the Time of Sun Rising, if the Sun has South Declination.
Let it be required to find the Time of the Sun's Rising and Setting, with the Length of the Day and Night, in Latitude 519 North, the 18th of July, 17962
I first seek the Sun's Declination for the given Day, and find it 200 53' North, which I here call 219, then under the Declination 21, and against the Latitude 510, stands 7 Hours, 53 Minutes, the Time the Sun sets on the given Day, in Lat. 51 North, which being doubled, gives 15 Hours, 46 Minutes, the Length of the Day; and if 7 Hours, 53 Minutes, the Time of Sun-setting, be subtracted from 12 Hours, the Remainder 4 Hours, 7 Minutes, gives the Time of the Sun's Rifing, which being doubled, gives 8 Hours, 14 Minutes Length of the Night. But, when the Sun has 21° South Declination in this Latitude, the Time of Sun Setting becomes the Time of Sun Rising, and the Length of the Day will then become the Length of the Night. -
Thus, the 25th of November, 1796, the Sun's Declination is 20° 59' South, or 21°, then the Time of Sun Rising is 7 Hours 53 Minutes, his Setting 4 Hours 7 Minutes, and the Length of the Night 15 Hours 46 Minutes, and Day 8 Hours 14 Minutes.
Sun Rising doubled is the Len. of Night 528|And 6 H. 54 M. doub. is Len. of Night 13 48
To find the Rifing and Setting of the Stars.
By this Table the Rising and Setting of any Star may be found, whose Declination does not exceed 23° 30' North or South, in the following Manner.
If you are in North Latitude, and the Star has North Declination, look for the Declization at the Top, and the Latitude in the Right or Left Hand Columns, in the Angle of Meeting, is Half the Time of the Star's Continuance above the Horizon, in that Latitude; or the Time it takes in Ascending from the Eastern Side of the Horizon to the Meridian, and Descending from the Meridian to the Western Part of the Horizon.
Therefore, if these Hours and Minutes be subtracted from the Time of the Star's coming to the Meridian, the Remainder will be the Time of the Star's Rising, and if added, the Sum will be the Time of the Star's Setting.
1 48 Added, gives the Time of the Star's Setting 17 22 I 2
Star sets 22 Minutes after 5 in the Evening 5 22
When the Latitude is North, and the Star has South Declination, or the Latitude South and the Star has North Declination; find the Latitude in the Side Columns as before, against which, and under the Degrees of Declination, stands Half the Time the Star is under the Horizon, which being subtracted from 12, the Remainder will be Half the Time the Star will be above the Horizon in that Latitude. Example. What Time will the Dog Star, Sirius, Rise and Set at London, Jan. 25?
I 2 ry Under the Declination 160 26 S. and against Lat. 51° 32' or 52° stands 7 26 Half the Time the Star is above the Horizon - - 4 34. The Star comes to the Meridian in the Evening, at I o os Which Subtracted, shews that the Star Rises at 31 M. after 5 in the Evening 5 31