23d of September, the circle defcribed by the fun was at an equal diftance from both of the poles. This circle, therefore, muft divide the earth into two equal parts, and on this account was called the Equator or Equaller. It was alfo called the Equinoctial Line, because the fun, when moving in it, makes the days and nights of equal length all over the world. Having alfo obferved, that, from the 21ft of June to the 22d of December, the fun advanced every day fowards a certain point, and having arrived there, returned towards that from which he had fet out, from the 22d of December to the 21ft of June-they fixed thefe points, which they called Soltices, because the direct motion of the fun was ftopped at them; and reprefented the bounds of the fun's motion by two circles, which they named Tropics, because the fun no fooner arrived there than he turned back. Aftronomers, obferv

ing the motion of the fun, found its quantity, at a mean rate, to be nearly a degree (or the 360th part) of a great circle in the heavens, every twenty-four hours. This great circle is called the Ecliptic, and it paffes through certain conftellations, diftinguished by the names of animals, in a zone called the Zodiac. It touches the tropic of Cancer on one fide, and that of Capricorn on the other, and cuts the equator obliquely, at an angle of twenty-three degrees twenty-nine minutes, the fun's greateft declination. To exprefs this motion, they fuppofed two points in the heavens, equally distant from and parallel to this circle, which they called the Poles of the zodiac, which, turning with the heavens, by means of their axis, defcribe the two polar circles. In the artificial sphere, the equinoctial, the two tropics, and two polar circles, are cut at right angles by two other circles called Colures, which ferve to mark the points of the folftices, equinoxes, and poles of the zodiac. The ancients also observed that when the fun was in any point of his courfe, all the people inhabiting directly north and fouth, as far as the poles, have noon at the fame time. This gave occafion to imagine a circle paffing through the poles of the world, which they called a Meridian, and which is immoveable in the artificial fphere, as well as the horizon, which is another circle representing the bounds betwixt the two hemifpheres, or half spheres, viz. that which is above, and that which is below it.

By the GLOBE is meant the reprefentation of the different places and

countries on the face of the earth, upon an artificial globe or ball. Geographers have represented the fituation of one place upon this earth with regard to another, or with regard to the earth in general, by transferring the circles of the sphere to the artificial globe: and this is the only method they could employ. This will be abundantly obvious from an example. After that circle in the heavens, which is called the equator, was known to aftronomers, there was nothing more easy than to transfer it to the earth, by which the fituation of places was determined, according as they lay on one fide of the equator or the other. The fame may be obferved of the other circles of the fphere above mentioned. The reader having obtained an idea of the principle upon which the

itself, or, in other words, the defcription of our earth, as reprefented by the artificial globe.

FIGURE OF THE EARTH.] Though, in fpeaking of the earth with the other planets, it was fufficient to confider it as a spherical or globular body, yet it has been discovered that this is not its true figure, and that the earth, though nearly a fphere or ball, is not perfectly fo. This occafioned great difputes between the philofophers of the laft age, among whom fir Ifaac Newton and Caffini, a French aftronomer, were the heads of two different parties. Sir Ifaac demonftrated from mathematical principles, that the earth was an oblate Spheroid, or that it was flatted " at the poles, and jutted out towards the equator, fo that a line, drawn through the centre of the earth, and paffing through the poles, which is called a diameter, would not be fo long as a line drawn through the fame centre and paffing through the caft and weft points. The French philofopher afferted precifely the reverse; that is, that its diameter was lengthened towards the poles. In order to decide this question, the king of France, in 1736, fent out fome able mathematicians towards the north pole, and likewise others towards the equator, in order to measure a degree, or the three hundred and fixtieth part of a great circle, in thofe different parts; and from their report, the opinion of fir Ifaac Newton was confirmed beyond difpute. Since that time, therefore, the earth has always been confidered as more flat towards the poles than towards the equator. The reafon of this figure may be easily understood, if the reader fully comprehends what we formerly obferved, with regard to the earth's motion. For if we fix a ball of foft clay on a fpindle, and whirl it round, we shall find that it will jut out or project towards the middle, and flatten towards the poles. This is exactly the cafe with respect to our earth; only that its axis reprefented by the fpindle, is imaginary. But though the earth be not properly fpherical, the difference from that figure is fo fmall, that it may be reprefented by a globe, without any fenfible error.

CIRCUMFERENCE AND DIAMETER OF THE EARTH.] In the general table which we have exhibited, page 4, the diameter of the globe is given according to the beft obfervations; fo that its circumference is 25,038 English miles. This circumference is conceived, for the conveniency of measuring, to be divided into three hundred and fixty parts or degrees, each degree containing fixty geographical miles, or fixty-nine Englith miles and a half. Thefe degrees are in the fame manner conceived to be divided each into fixty minutes.

AXIS AND POLES OF THE EARTH.] The axis of the earth is that imaginary line paffing through its centre, on which it is fuppofed to turn round once in twenty-four hours. The extreme points of this line are called the Poles of the earth; one in the north and the other in the fouth, which are exactly under the two points of the heavens called the North and South Poles. The knowledge of thefe poles is of great ufe to the geographer in determining the diftance and fituation of places; for the poles mark, as it were, the ends of the earth, which is divided in the middle by the equator: fo that the nearer one approaches to the poles, the farther he removes from the equator; and in removing from the poles, he approaches the equator.

CIRCLES of THE GLOBE.] Thefe are commonly divided into the greater and leffer. A great circle is that whose plane paffes through the centre of the earth, and divides it into two equal parts or hemifpheres. A leffer circle is that which, being parallel to a greater, cannot pafs

through the centre of the earth, nor divide it into equal parts. The greater circles are fir in number, the leffer only four.

EQUATOR.] The firft great circle is the Equator or Equinoctial; and by navigators called the Line. The poles of this circle are the fame with thofe of the world. It paffes through the eaft and weft points of the world, and, as has been already mentioned, divides it into the northern and fouthern hemifpheres. It is divided into three hundred and fixty degrees, the use of which will foon appear.

HORIZON.] This great circle is reprefented by a broad circular piece of wood encompailing the globe, and dividing it into the upper and lower hemifpheres. Geographers very properly diftinguith the horizon into the fenfible and rational. The firft is that which bounds the utmost prospect of our fight, when we view the heavens around us, apparently touching the earth or fea.

This circle determines the rifing or fetting of the fun and ftars, in any particular place; for when they begin to appear above the eastern edge, we lay they rife; and when they go beneath the western, we fay they are fet. It appears that each place has its own fenfible horizon. The other horizon, called the rational, encompaffes the globe exactly in the middle. Its poles (that is, two points in its axis, each ninety degrees diftant from its plane, as thofe of all circles are) are called the Zenith and Nadir,-the former exactly above our heads, and the latter directly under feet. The broad wooden circle which reprefents it on the globe, has feveral circles drawn upon it: of these the innermoft is that exhibiting the number of degrees of the twelve figns of the zodiac (of which hereafter,) viz. thirty to each fign. Next to this, you have the names of thefe figns, together with the days of the month according to the old ftyle, and then according to the new ftyle. Befides thefe, there is a circle reprefenting the thirtytwo thumbs, or points of the mariner's compafs. The ufe of all these will be explained hereafter.

MERIDIAN.] This circle is reprefented by the brafs ring on which the globe hangs and turns. It is divided into three hundred and fixty degrees, and cuts the equator at right angles; fo that, counting from the equator each way to the poles of the world, it contains four times ninety degrees, and divides the earth into the eaftern and western hemifpheres. This circle is called the meridian, because, when the fun comes to the fouth part of it, it is then meridies or mid-day, and then the fun has its greateft altitude for that day, which is therefore called its meridian altitude. Now, as the fun is never in its meridian altitude at two places eaft or weft of one another at the same time, each of these places must have its own meridian, There are commonly marked on the globe twenty-four meridians, one through every fifteen degrees of the

equator.

ZODIAC.] The zodiac is a broad circle, which cuts the equator obliquely; in which the twelve figns above mentioned are reprefented. In the middle of this circle is fuppofed another called the Ecliptic, from which the fun never deviates in his annual course, and in which he advances thirty degrees every month: The twelve figns are,

COLURES.] If we imagine two great circles paffing both through the poles of the world, and one of them through the equinoctial points Aries and Libra, and the other through the folftitial points Cancer and Capricorn, these are called the Colures,-the one the Equinoctial, the other the Solstitial Colure.-These are all the great circles.

TROPICS.] If we fuppofe two circles drawn parallel to the equinoctial, at twenty-three degrees thirty minutes diftance from it, measured on the brazen meridian, the one towards the north, the other towards the fouth, these are called Tropics, from the Greek word rp, a turning, because the fun appears, when in them, to turn backwards from his former couple. The one is called the Tropic of Cancer, the other of Capricorn, because they pass through the first points of thefe figns.

POLAR CIRCLES.] If two other circles are fupposed to be drawn at the like distance of twenty-three degrees thirty minutes, reckoned on the meridian from the polar points, these are called the Polar Circles. The northern is called the Arctic, because the north pole is near the conftellation of the Bear, in Greek pros; the fouthern, the Antarctic, because oppofite to the former. And these are the four leffer circles. Befides thefe ten circles now defcribed, which are always drawn on the globe, there are feveral others which are only supposed to be drawn on it.

Thefe will be explained as they become neceffary, left the reader fhould be difgufted with too many definitions at the fame time, without feeing the purpose for which they ferve. The principal defign of all thefe circles being to exhibit the refpective fituation of places on the earth, we fhall proceed to confider more particularly how that is effected by them. It was found easier to distinguish places by the quarters of the earth in which they lay, than by their distance from any one point. Thus, after it was difcovered that the equator divided the earth into two parts, called the Northern and Southern hemifpheres, it was easy to fee that all places on the globe might be diftinguished, according as they lay on the north or fouth fide of the equator.

ZONES.] After the four leffer circles we have mentioned came to be known, it was found that the earth, by means of them, might be divided into five portions, and confequently that the places on its furface might be diftinguished according as they lay in one or other of thefe portions, which are called Zones, from the Greek word wvn, which fignifies a girdle; being broad spaces, like swathes, girding the earth about.

The torrid zone is that portion of the earth between the tropics, and called by the ancients torrid, because they conceived, that, being continually exposed to the perpendicular or direct rays of the fun, it was rendered uninhabitable, and contained nothing but parched and fandy deferts. This notion, however, has long fince been refuted. It is found that the long nights, great dews, regular rains and breezes which prevail almoft throughout the torrid zone, render the earth not only habitable, but fo fruitful, that in many places they have two harvests in a year; all forts of fpices and drugs are almoft folely produced there; and it furnishes the moft perfect metals, precious ftones, and pearls. In fhort, the countries of Africa, Afia, and America, which lie under this zone, are in all refpects the most fertile and luxuriant upon earth.

The two temperate zones are comprifed between the tropics and polar circles. They are called temperate, because, meeting the rays of the fun obliquely, they enjoy a moderate degree of heat.

The two frigid zones lie between the polar circles and the poles, or rather are inclofed within the polar circles. They are called the frigid or frozen, because moft part of the year it is extremely cold there, and