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marked Equation of Time, shows when, and how much, the Sun is fast or slow by the clock.

I have not room to enter into the particulars, of this subject, as much as I could wish; but in the next number of the Almanac I hope I shall be able, with the assistance of my friend Jonathan Downes, to explain this, as well as some other interesting particu lars connected with Astronomy, in such a manner as to make them perfectly understood. Now for some examples; but first, be sure you understand what has been already advanced. If you do not, read it carefully over once or twice more; the difficulty is not that the subject is above your comprehension, but that you may not recollect all the necessary particulars.

We will find the time of the Sun's rising at Boston on the 2d of March. Against this day, in the calendar page for March, we find the Sun declination to be 7° 4' south. As the 4' are less than a quarter of a degree, and would not materially affect the calculation, we neglect them, and call the declination 7° S. With this we look in the table for south declination, and against it, under Boston, &c. we find 6h. 25m. In the small table for semidiameter and refraction we find against 6°, being nearest 70, and under Boston 4m. 22s. which we subtract from 6h. 25m., the remainder is 6h. 20m. 38s. This is the time of sunrise according to apparent time; we will now correct it for mean time, or, the time by the clock. In the column, Equation of Time, of the calendar for March; we find that on the 2d, the Sun is 12m. 21s. slow. Now as the Sun is after the clock, it is evident that this equation must be added. We therefore add it to the time, corrected for refraction 6h. 20m. 28s. and thus find that the Sun rises at 6 o'clock, 32 minutes and 49 seconds. For sunset on the same day, we find the time shown by the table to be 5h. 35m., to this we add the correction for semidiameter and refraction, also the equation as before, and find the time to be 5 o'clock, 51 minutes, 43 seconds. Required the time of sunrise at Boston,

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April 20? Ans. 5h. 11m.
24? แ 4 59

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Eastport,
Washington, Dec. 12?

sunset at Charleston, S. C. July 15?
Eastport,

66

May 28?

Remember to add the equation when the Sun is slow, or after the when fast, or before the clock.

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We will now try the operations with the Moon. Here we must use only the time given in the tables for setting, considering it the time from her rising to her southing, or from her southing to her setting.

We will find the time of the Moon's rising at Eastport, April 10th. By looking in the column of her declination, we find it on that day, at rising, to be 22° 4' south, say 220 south. By referring to the table for south declination, we find the time to be 4h. 25m. To this, must be added 10 minutes correction found in the column next to th right of the Moon's southing. This makes it 4h. 35m. which is now to be taken from her southing, 8 o'clock morning. The remainder is 3h. 25m. the time of her rising o the 10th. We will now find the time of her rising at Boston on the 5th of April. declination is 27° 28' S. Time corresponding in the table 3h. 55m. correct making it 4h. 6m. As the time of her southing on the 5th is 3h. 1m

4h. 6m. taken from it will carry the time back to the evenin

not the time of her rising on the 5th. By consideri

6m. must be taken from the time of her southi

morning; now subtract from this, borro

of her rising the evening previous; th

from west to east, souths at a mear
day. Consequently there must be
south; the same may be said of
rises at 11h. 54m. on the 5th.
an interval of 24h. and 50m. elapses;

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ing, but early in the morning of the 7th, consequently the Moon will not rise at all on the 6th. For example, required the time of the Moon's rising on the 6th. Her declination at the time of her next rising after the 5th is 26° 40' S. corresponding time 4h. 13m. add the correction 11m. equal 4h. 24m. This, taken from the time of her next southing 5 o'clock 2m. on the morning of the 7th leaves 49m. Thus it appears she does not rise on the 6th, but at 49 minutes past 12, or midnight, making it the morning of the 7th. To understand this well, may require a careful reconsideration of all the circumstances of the case; but be sure you do understand it before you proceed. In every case consider whether you are to subtract the time taken from the tables with the correction from the calendar column, marked Corrections for Table,' added; from the time of the Moon's southing on the given, or the next day. The correction in minutes, from the calendar pages; is, in all cases, to be added to the time taken out of the tables, before

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