221. By Table I. at the close of this Sect. the Dominical Letter for any year, (New Style,) within 4,000 years following the Christian ærą, can be readily found. Look for the hundreds of years at the head of the column, and for the years below a hundred to make up the given year) at the left hand. Thus, if I want to know the Dominical Letter for 1822, I look for the column containing 1800 at the top; and in that column, opposite 22 in the left hand column, I find the Dominical Letter of that year, viz. F. Again, if I want to know the Dominical Letter for 1940, I find the column containing 1900 at top, and in that column, against 40 in the left hand column, are G and F, which are the Dominical Letters for that year. Because there are 2 letters against that year, I know it is a leap year.

222. Having the Dominical Letter for any year, Table II. shows what days of every month in the year will be Sundays ; whence may be readily seen what day of the week falls upon any given day in the year. For under the Dominical Letter at the top are the Sundays of that year; and next to the Sundays, on the right, are the Mondays, and next are the Tuesdays, and so on to the last column; from which go to the left hand column, and proceed as before to the right hand. Thus, if I want toibpow what day of the week falls on the 1st of Sept. 1822, I find the Dominical Letter of that year to be F, and under F, against the Month Sept, I find the 1st day. Hence the 1st day is Sunday, the 2d Monday, and so on. Again, to kņow what day of the week will fall on the 15th day of July, 1831, bý Table 1. I find the Dominical Letter of that year is B; in Table II. under B, and against July, I find that Sunday falls on the 10th, consequently the 15th will be Friday,

Let the pupil be exercised in solving questions by these TABLE) till their application becomes easy.

TABLE I.

Showing the Dominical Letter, New Style, for 4000 years after the Christian æra.

Week days. ABCDEFG

TABLE II.

Showing the days of the months, for both Styles, by the Dominical Letters.

1 2 3 4 5 6 7

8 9 10 11 12 13 14 January 31 15 16 17 18 19 20 21 October 31 22 23 24 25 26 27 28

29 30 31

1 2 3 4

5 6 7 8 9 10 111 Feb. 28-29 12 13 14 15 16 17 18! March 31 19 20 21 22 23 24 25 November 30 26 27 28 29 30 31

1 2 3 4 5 6 7 8

9 10 11 12 13 14 15 April 30 16 17 18 19 20 21 22 July 31 23 24 25 26 27 28 29

30 31

1 2 3 4 5 6 7 8 9 10 11 12

113 14 15 16 17 18 19 August 31 20 21 22 23 24 25 26 127/28/29/30/31

12) 3 4 5 6 7 8 9

10 11 12 13 14 15 16 September 30 17 18 19 20 21 22 23 December 31 24 25 26 27 28 29 30

31

Sect. VII.

Of Epact.

223. A Julian year consists of 365 days, 6 hours, and a lunar year, of 12 moons, consists of 354 days, 8 hours, 49 minutes. This difference of nearly 11 days between a solar and a lunar year is the Annual Epact. Since the epact of one year is 11 days, the epact of two years is 22 days, of three years is 33 days, or rather 3 days; being 3 days over a complete lunation. Hence the epact of four years is 14 days. Thus by yearly adding 11, and casting out the 30s for intercalary lunations, (for when 30 is cast out, the lunar year must consist of 13 lunations, it will be found, that on every 19th year 29'remains; which is reckoned a complete lunation, and the epact is 0. Thus the cycle, or succession of epacts, expires with the Golden Number, or lunar cycles; and on every 19th year the solar and lunar year begin together. By the epact of any year, the moon's age, or the number of days since her change, is at once seen, for the first day of January. In the following TABLE is exhibited the Golden Numbers, with the corresponding epacts, till the year 1900 of the Christian æra.

224. The INDICTION is a revolution of 15 years, used only by the Romans for indicating the times of certain

payments made by the subjects to the Republic. By the multiplication of the Cycle of the Sun (28 years) into the Cycle of the Moon (19 years) and the Indiction (15 years) arises the Great Julian Period, consisting of

1980 years.

A few of the most useful and interesting Problems are here inserted, for such pupils as have globes at hand, and instructers, who can point out and explain the use of the different circles and appurtenances belonging to them.

ART. 1.
Problems to be solved by the Terrestrial Globe.

225. PROB. 1.--To find the latitude of any given place.

Bring the place to the graduated side of the brazen meridian, and the degree of the meridian over the place is the latitude.

1. What is the latitude of Boston ? Ans. 42° 28' N.

2. Find the latitude of
Amsterdam, Constantinople, Quebec,
Aleppo,
Florence,

Rome,
Alexandria, Cape Farewell, Stockholm,
Athens,

C. of Good Hope, Savannah,
Bourbon isl. Lima,

Tripoli,
Bayonne, New Orleans,
Barbadoes isl. Naples,

Vienna,
Canton,
Panama,

Warsaw,
Cairo,
Paris,

Washington. 226. Prob. II.-To find the longitude of a given place.

Bring the place to the brazen meridian, and the degree of the equator under the meridian is the longitude.

Upsal,