being greater at a small distance and smaller at a great distance. Its power is found to diminish as the squares of the distances increase. Thus, if at the distance of 10,000 miles, the attractive force be considered as 4, at the distance of 20,000 it will be only 1. Hence the waters on the side of the earth directly under the moon are more attracted by the moon than the central parts of the earth, because they are nearer to the moon, and the central parts of the earth are more attracted than the waters on the opposite side of the earth. Consequently the waters directly under the moon will be as it were attracted from the centre of the earth and be made to rise towards the moon; and the centre of the earth will be as it were attracted from the waters on the side of the earth opposite to the moon, so that those waters will be less near the earth's centre than if the moon did not operate, i. e. they will rise. On the meridian directly under the moon, therefore, there will be a high tide and a similar one on the opposite side of the earth, at the distance of 180°. On each side, however, at 90° distance from that meridian, in consequence of the moon's very oblique attraction, the waters will be depressed.

The tides are higher than ordinary twice a month, viz. about the times of the new and full moon; and these are called spring tides. Because at these times the attraction of the sun conspires with that of the moon, or their agency is in the same right line; and consequently the tides must be more elevated. When the two luminaries are in conjunction, or on the same side of the earth, they both conspire to raise the water on the nearest and remotest part; and when they are in opposition, that is, when the earth is between them, the part nearest to the one is remotest from the other, and vice versa, consequently the effects of their agency are united.

The tides are less than ordinary twice a month; that is, about the times of the first and last quarters of the moon; and these are called neap tides. For in the quarters of the moon, the sun raises the water where the moon depresses it; and depresses it where the moon raises it; the tides are made therefore by the difference of their actions.

LENGTH OF MILES IN DIFFERENT COUNTRIES.

There is scarcely a greater variety in any thing than in this sort of measure; not only those of separate countries differ, as the French from the English, but those of the same country vary in the different provinces, and all commonly from the standard. Thus the common English mile differs from the statute mile, and the French have three sorts of leagues.

We shall here give the miles of several countries, compared with the English, by Dr. Hally.

The English statute mile consists of 5280 feet, 1760 yards, or & furlongs.

Eleven Irish miles are equal to fourteen English.

The Russian verst or werst is little more then English.

The Turkish, Italian, and old Roman less, mile is nearly 1 En

glish.

The Arabian, ancient and modern, is about 11 English.

The Scotch mile is about 1 English.

The Indian is almost 3 English.

The Dutch, Spanish, and Polish, is about 3 English.

The German is more than 4 English.

The Swedish, Danish, and Hungarian is from 5 to 6 English.

The French common marine league is nearly 3, and

The English marine league is 3 nautical miles.

The East used another span equal to one third of a cubit. The above are sacred measures, in the lengths of which there must necessarily be some degree of uncertainty. Arbuthnot makes

the sacred cubit equal to 1·7325 feet. He also observes, that the Jews sometimes made use of a profane cubit, the length of which he determined to be 1·485 feet.

DIFFERENT TIMES WHEN THE DAY BEGINS; AND A SHORT ACCOUNT OF THE OLD AND NEW STYLE.

The ancient Egyptians and Romans supposed the day to begin at midnight; and it is also now considered by the United States of America, Great-Britian, France, and most European countries, as beginning at that time. In Astronomy, however, it is supposed to begin at noon, or the time when the sun is on the meridian. The beginning has been fixed at sunrise by some nations, as the ancient Babylonians, Persians, &c. and at sunset by others, as the ancient Jews, Grecians, &c.

In the Julian calendar or old style, a method of reckoning time, adopted by Julius Cæsar, about 45 years before the birth of Christ, which was much preferable to any that preceded it, a year was supposed to consist 365 days and 6 hours; each of 3 years in succession was considered as a common year of 365 days, and on account of the annual excess of 6 hours, another was added to every fourth, which consequently consisted of 366 days, and was called leap year. As the solar year, or the time of the apparent annual revolution of the sun, is not exactly 365 days and 6 hours, but nearly 365 days, 5 hours, 48 minutes and 48 seconds, it follows, that the Julian year exceeded the solar by about 11 minutes and 12 seconds. This annual excess amounts to 1 day in 129 years. Notwithstanding this inaccuracy, the Julian style was generally used in Europe till the year 1582, when it was reformed by Pope Gregory the thirteenth, who introduced what is called the Gregorian or new style.

It having been found that the vernal equinox, which had been fixed to the 21st of March by the council of Nice, held in the year 325, happened the 11th of March in 1582, the difference of 10 days between the civil and real time was taken from the October of that year, and the 21st of the next March reduced to the true time of the equinox. But the Protestant states refused, at that time, to accede to the new style, which the Pope had enjoined on all the ecclesiastics within his jurisdiction, and exhorted the Christian princes to adopt in their respective dominions; and it did not commence in the British empire, of which the present United States of America then made a part, till the year 1752, when the error having increased to 11 days, they were, by an act of parliament, struck out of the calendar from the month of September, the third day, according to the old style, being called the fourteenth.

The reformation of the calendar consisted not only in expunging the excess of the civil above the real time, but also in the introduction of a principle which should prevent a like accumulation of error in future. According to the old style the last

year

of every century is a leap year, but in the new only every fourth of these leap years is retained, the rest being considered as common years. This diminution of the number of leap years nearly balances the error, which, at the rate of 11 minutes and 12 seconds a year, amounts to 1 day in 129 years, and 3 days in about 4 centuries.

It is, however, to be observed, that at the above annual rate of 11 minutes and 12 seconds, the accumulation in 4 centuries is 3 days, 2 hours, and 40 minutes, so that the deduction of 3 days in 4 centuries, falls short of the difference between the civil and real time by 2 hours and 40 minutes, which error will become equal to 1 day in 36 centuries.

UNIVERSAL GEOGRAPHY.

THE EARTH.

Extent.] The surface of the globe is estimated to contain 197, 000,000 square miles, of which more than 50,000,000, or one quarter of the whole, is land.

Natural Divisions.] The great natural division of the earth's surface is into Land and Water.

1. The land consists of continents, islands, peninsulas, isthmuses, capes, mountains, hills, and valleys.

A Continent is a great extent of land, no where entirely separated by water. There are two continents; the Eastern and the Western. The Eastern continent is subdivided into Europe, Asia, and Africa; the Western, into North America and South America. An island is a portion of land smaller than a continent, entirely surrounded by water; as Great Britain, Newfoundland, Cuba, Madagascar.

A peninsula is a portion of land almost surrounded by water, as Spain, Florida.

An isthmus is the narrow neck of land which joins a peninsula to the main land; as the isthmus of Darien, the isthmus of Suez. A cape is a point of land projecting into the sea; as Cape Cod, Cape Horn.

A mountain is a portion of land elevated to a great height above the surrounding country. When the land rises to a small height it is called a hill. The spaces between hills are called dales or valleys. A volcano is a burning mountain which emits smoke and flame.

2. The water is composed of oceans, lakes, seas, sounds, bays or gulfs, harbors, roads, straits, rivers and friths or estuaries.

The largest collections of water on the globe are called oceans. There are five oceans; the Indian ocean, lying between Africa, Asia, and New-Holland; the Atlantic, between America on one side and Europe and Africa on the other; the Pacific, between America on one side, and Asia and New-Holland on the other; the Northern or Arctic, around the north pole; the Southern, around the south pole.

A lake is a collection of water in the interior of a country, as Lake Superior, Lake Erie.

A sea is a large collection of water communicating with an ocean, as the Mediterranean sea, the Baltic.