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weftward of the meridian, when it is high water on fuch days, the tide is faid to flow on fuch a point; fo, if the moon bear foutheaft, at high- water, it is faid to flow fouth-eaft and north-weft, or 9 o'clock; if he bears fouth-weft, it flows fouth-weft and north-east, or 3 o'clock; and in like manner for every other point of the moon's bearing.

From the obfervations of many perfons, the time of high-water on the days of the new and full moon on moft of the coafts of Europe, and several other places, have been collected; and thofe are generally put in a table, against the names of their refpective places, in an alphabetical order; hence it is called the Tide Table. which is at the end of the Book.

The method generally prefcribed for finding the time of highwater at any place, is contained in the following particulars:

To find the Leap Year.

Divide the given year by 4, if nothing remains, it is leap-year, but if 1, 2, or 3 remains, they fhew that it is fo many years after Biflextile or Leap-year, as the remainder is: thus, in the year 1806, divided by 4, gives 451, and the remainder [2] fhews it is the second year after Biffextile, or Leap-year.

To find the Golden Number for any Year.

RULE. Add one to the given year, and divide the fum by 19, the remainder will be the Golden Number.

EXAMPLE.

Required the Golden Number of 1806 ?

By adding one to that year, it gives 1807; this divided by 19 gives 95 for the quotient, and the remainder is 2, the Golden Number for 1806.

To find the Epact for any Year.

NOTE. The Epact is the moon's age at the beginning of the year, or rather the ift of March. The Epact advances II every year to 30, because the folar year is 11 days longer than the lunar year, and as the Epact increases, it fhews the moon's age at the beginning of the year; it is here fuppofed that at the end of 19 years, the fun and moon make all the variety of fituations they poffibly can with one another, and thence begin, and go over the fame again. The Golden Number at the birth of Chrift was 1, which is the reason that one is added to the given year, to find the Golden Number.

RULE. Divide the given year by 19, the remainder multiply by I, and the product will be the Epact, if it does not exceed 29; but if it does, fubtract 30 from it as often as you can, and the remainder will be the Epact, for it never exceeds 29.

EXAMPLE.

What is the Epact of the Year 1806?

1806 divided by 19, gives 95 for the quotient, and I remaining fhews the Epact is (11) for 1806.

To find the Moon's Age.

To the Epact add the day of the month, and the Epact or number for the month; the fum, if it does not exceed 30, is her age; but if it does, fubtract 30 from it as often as you can, and the remainder is her age.

NOTE. The Epact, or number for each month, is found thus: divide the number of days contained between the 1ft of January and the ift day of any month, by 29, the remainder will be the number for that month.

Required the Number or Epact for Sept. 1806?

The number of days contained between the 1ft of January, 1806, and the ift of Sept. are 243 days, divided by 291, gives 8 for the quotient, and 7 for the remainder, which is the number fought; and fo for any other month.

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In 'com. years

In leap years

Jan. Feb. Mar. Apr. May June July Aug. Sept. O&t. Nov. Dec. 2 4 4 6 7 8 9 19 9 10 II

2

2

O 2 1

3

3 5 5 7 8

To find the Moon's Southing on any Day of her Age.

Since the fun returns to the meridian he has left in the space of 24 hours, and the moon in about 24 hours 49 minutes; therefore, if the moon leaves the meridian at the fame time that the fun does, on any day, the next day fhe will come to the meridian 49 minutes after him, falling back about 49 minutes every day; whence, to find the time of the moon's fouthing, or coming to the meridian on any day, we have this eafy RULE:

Multiply the day of her age by 49, and divide the product by 60, the quotient is the hours, and the remainder the minutes afternoon when she fouths. Or, which is rather eafier, and in many refpects fufficiently exact for the mariner's purpofe; multiply the

moon's

moon's age by 4, and divide the product by 5, the quotient is the hours, and the remainder multiplied by 12, gives the minutes afternoon when the is upon the Meridian; but if this time exceeds 12, fubtract 12 hours from it, and the remainder is the time of her fouthing in the morning.

N. B. From the full moon to the change fhe comes to the meridian, or fouths, in the morning; but from the change to the full, in the afternoon.

EXAMPLE.

Required the Moon's Southing, Aug. 14, 1806?
The Epact is

Number for the month is

Day of the month

Moon's Age

II

6

14

30)31(1

I = 49 min.

Hence it appears that the moon comes to the fouth at 49 minutes afternoon.

To find the Time of High Water on any Day of the Moon's Age at any Place.

RULE. To the time of the moon's fouthing on the given day, add the time of high-water at the full and change, at the given place, taken from the Table; the fum is the hour paft noon on the given day when it is high-water at that place; and if this hour exceeds 12, fubtract 12 from it, and the remainder fhews the time of high water in the morning; but if it exceeds 24, fubtract 24 from it, and the remainder fhews the time of high-water in the afternoon.

Required the Time of High Water at Milford on the 29th Jan. 1806. EXAMPLE I.

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EXAMPLE III.

Here it is 36 min. past two

o'clock in the afternoon.

EXAMPLE IV.

Required the Time of High Water at Aberdeen on the 2d of June, 1806.

No. of Month
Day of Month

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In the Morning

Required the Time of High Time at Aberdeen
Water at Dover, Oct. 1, 1806.

19)1806,95

H. W. Morning

13.36
12.45

26. .21

24.

2.21

Coming into a Port and finding that it is High Water at a certain Hour,

to know when it is High Water there on Full and Change Days. RULE. Subtract the time of high-water from the moon's fouthing on that day, but if required add 12 hours, the remainder will be the time of the flowing, on the full and change, at that place.

Epact

II

4

2

Moon's Age
× by

17

4

by

5)68(3

12

This method of finding the time of high-water, at times, will differ hours wide of the truth; even if the moon's fouthing be exactly found; for the floods do not always happen at the fame diftance of time from each other, but at different diftances. according to the times of the moon's age, or as the waters are acted upon by the fum or difference of the attractive forces of the fun and moon, and alfo on account of winds and ftorms, even when out of hearing; therefore pilots, and all concerned, would do well to ufe the following method, which will in general give the time of high-water nearer the truth, when the tides are not greatly influenced by the wind.

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Find the day and hour of the laft new moon which happened before the day propofed; to which add the number of days elapfed, to find the moon's age.

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