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The artificial day is the time of light, or of the sun's appearance above the horizon in opposition to which, the time of darkness, or of the sun's continuance below the horizon, is called night.

The natural or civil day, is that space of time wherein the sun completes his circuit round the earth; or, to speak properly and astronomically, the time of an entire revolution of the equator. This period is the positive appointment of infinite Wisdom, whose prolonged operations we call the course of nature.

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The revolution of the earth on its axis causes a seeming revolution of the sun, and thus forms a measure of time, which we call a day; this is evidently founded on nature, and is the consequence of our observation of the sun but as the sun seems always alike, and never varies its form or general aspect, the eye does not derive from him the means of computing longer periods of time; for this, it turns to the moon, whose appointment being to enlighten night, and who" nightly changes in her circling orb. the notice of these changes becomes the register of a period of time, longer than what can be gathered from the sun. There are four particular instances of the moon's course, which are so peculiarly marked, it is impossible to mistake or confound them; first, when it is just visible in a small crescent in the evening; secondly, when it is exactly bisected, having the light to the right hand; thirdly, when it is full; and fourthly, when it is exactly bisected, having the light to the left hand. These correspond nearly to every seventh day, whereby they furnish the measures of that period of time we call a week, and, united, form the still longer period of a month. By months, was long the prevailing mode of reckoning; as requiring no trouble, no calculation; simply an inspection of the nightly luminary, and a correspondent memorandum of her aspect.

Months and weeks evidently began together, being regulated by the course of the moon; but nations acted with great diversity, in fixing the beginning of their days; some computing from the rising, others from the setting of the sun, others from noon, others from night. The ancient Babylonians, Persians, Syrians, and most other eastern nations, the Greeks, &c. began their day with the sun's rising; the ancient Athenians and Jews, the modern Aus

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trians, Bohemians, Silesians, Italians, and Chinese, from the sun's setting the ancient Umbri and Arabians, with the modern astronomers, from noon the Egyptians and Romans, with the modern English, French, Dutch, Germans, Spaniards, and Portuguese, from midnight.

A year truly contains 365 days, 5 hours, and 49 minutes but the most ancient form of the year, is that which divides it into 360 days.

EPOCHS are certain fixed points from which computations are begun, and to which calculations are referred. By comparing transactions with the epoch, and tracing their distance from it, we ascertain the years in which they happened, and assign them their place in the succession of time. But it is evident this can respect only the epoch to which they are referred, as the epoch of one nation is disregarded by others. The Creation of the world, the Deluge, the Olympiads, the Building of Rome, and the Birth of Christ, are all celebrated eras in history.

MEASURES.

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THE measures, most commonly made use of in geographical books, are miles and leagues. The English and Americanmiles consist of 8furlongs, equal to 1760 yar The marine league contains 3 miles. The Turkish, Ital ian, and old Roman mile differs but little from that of the English. The Dutch, Spanish, and Polish mile is about 3 English. The German is more than 4; the Danish and Hungarian, more than 5; and the Swedish nearly 7 English miles.

The marine or geographical mile is longer than the common, or English mile. In a degree of the earth's circumference, there are geographical miles, which are qual to 69% English miles.

In calculating the distance of places, by degrees of longitude, geographers generally assume the capital, or some other remarkable place of their own country, as the fixed meridian. Thus the French reckon their longitude from the meridian of Paris, and the English reckon theirs from Greenwich, which is the seat of the Royal Observatory. In the present work, the longitude, where it is not other

wise expressed, is calculated from the meridian of Philadelphia, which is 75° 8' 45' west from Greenwich.

The length of Miles, Leagues, Sc. ancient and modern, in English yards.

Ancient Roman mile

Yards. 1610,348

German rast, or common league in France,=? Gal.leuca 4331,044

Persian parasang=2 Gallic leagues

4831,044

Egyptian shane-1 ancient Roman miles

6441,892

German league, or that of Scandinavia rasts

9662,083

The mile or league of Germany 200 Rhenish yards

8239,846

Great Arabian mile, used in Palestine, in the time

Modern Roman mile

the Crasades, rated at 14 ancient Ruinam intime of 2415,713

Modern Greek mile, of 7 Olympic stadia

Modern French league 2500 toises

Mile of Turkey, and the common west of Russia,

supposing it 7 Olympic stadia

League of Spain-1 ancient Roman miles

Large league of Spain= ditto

1623,466

1409,0545

5328,75 1409,0515

6441,342 8051,74

OF THE LOG LINE.

A LoG is a piece of board, in the form of the quadrant of a circle, having its circular side loaded with weights, to make it swim upright. To this log is fastened a line of about 150 fathoms, called the log line; this is divided into equal spaces, called knots, each of which ought to bear the same proportion to a nautical mile, as a minute bears to an hour. They are called knots, because at the end of each of them there is fixed a piece of twine with knots in it; and these are subdivided into tenths. Now a nautical mile=6120 feet, and the r part-51 feet; now : 1 hour: 51 feet: 6120 feet, or a mile; therefore, if 51 feet of the log line run off in, one mile will be run off in an hour; hence, as many knots as are run off in an

hour, so many miles the ship sails in an hour. But as the ship's run is found to be more than that given by the log, owing to the log being drawn forward, they generally allow only 50 feet for a knot; and some commanders allow less. And to measure the time, they have a sand glass, which runs out in half a minute.

The line runs off a reel, which turns very easily, and the log is thrown from the poop, or lee quatter; and they generally let it run 12 or 15 fathoms, so as to be out of the ship's wake, and then begin to count. There is com. monly fastened a piece of red flag, to show where you are to begin to reckon. Care must be taken to have the hour glass and log line correct, otherwise an allowance must be made.

If the log line and the time of the running out of the glass be both altered in the same proportion, the number of knots run out in one glass will still show the number of miles run in an hour; for if the knots be 40 feet and the glass run out in 24", then 24" 30':: 40 feet: 50 feet, so that 50 feet is still run out in half a minute.

RAIN GAGE.

The RAIN GAGE is an instrument to shew the quantity of rain which falls upon the earth at any place where you may wish to make observations. By this instrument (which is described in the large Geography p. 84) the mean annual depths of rain in inches at the places below, has been determined.

GEOGRAPHY MADE EASY.

AMERICA.

OF the grand divisions of the earth, America is much the largest. From its late discovery, by the inhabitants of the eastern continent, it is frequently denominated the New World, or New Hemisphere, a title, which, perhaps, it may justly claim, when we consider its vast extent, and its unquestionable superiority over any other division of the earth, in the number and variety of its products, and the interesting consequences it has already produced, and is still producing, with respect to the nations of the world.

Situation and Extent. The southern limit of the American continent is in 56° south latitude, whence it extends probably to the north pole. Of the northern limit, however, we cannot speak positively, as no discoveries have been made beyond 72 or 73 degrees of north latitude. Its length from north to south, may be estimated at 9600 miles. It spreads from the 35th to 168th degree west longitude from London. Its breadth is very unequal, but supposed to average 1500 miles, though in the northern part it is known to exceed 4500.

nent.

America is in no part joined by land to the old contiIt is separated from Europe and Africa on the eastby the Atlantic ocean: the Pacific ocean divides it from Asia on the west. It contains upwards of 14,000,000 square miles.

Divisions. Though America forms properly but one continent, yet there is a division so clearly marked by nature, that the propriety of its being considered in two separate portions is universally acknowledged. These two regions, called North and South-America, are joined togeth