countries in both situations to be equally uninhabitable. Since the globe, however, has been farther explored, it has been found that many places, which lie directly under the equator, are extremely populous, notwithstanding the excessive heat of the climate; and even the bleak regions of the pole are not wholly desolate; so that the following description of those parts must be considered as more poetical than just.

"The fields of liquid air, inclosing all,

Surround the compass of this earthly ball:
And as five zones th' etherial regions bind,
Five, correspondent, are to earth assign'd:
The sun, with rays directly darting down,
Fires all beneath, and fries the middle zone :
The two beneath the distant poles complain
Of endless winter, and perpetual rain:
Betwixt th' extremes, two happier climates hold
The temper that partakes of hot and cold."

OVID.

Having fixed the position of the poles and equator, it will be easy to form a notion of any other circles that can be drawn upon the globe. A meridian, for instance, is a certain great circle, which is supposed to pass through the two poles, and to divide the eastern half of the earth from the western half. And because any place, which lies to the east or west of another, may have a circle of this kind drawn through it, you will readily perceive that there may be as many meridians as there are places of different situations. The meridian of any particular place is also to be known, by its being that circle in which the sun is always to be found

at noon, or when he is at an equal distance both from the point where he rises, and that where he

sets.

But what has been here described, will perhaps be better understood from the following figure, (Pl. 111. fig. 2.) where the line SN represents the axis of the earth, or that line about which its diurnal revolution is performed, N and s, the north and south poles, and EQ, the equator; also SAN, SBN, SCN, &c. are meridians passing through the north and south poles, and each dividing the earth into an eastern and western hemisphere, the same as the equator EQ, divides it into a northern and southern hemisphere.(g)

These are the principal circles concerned in the present subject; and if they be properly understood, what follows will be found perfectly easy. The equator, for instance, is represented as a boundary, which separates the northern from the southern hemisphere; and the latitude of a placę is its distance north or south from this circle. If the place lies in the northern hemisphere, it is said to have north latitude; and if it lies in the southern hemisphere, it is said to have south latitude: so that the latitude of any place will be greater or less, according as it is farther from, or nearer to the equator. And in order to estimate this distance, we conceive a meridian to be drawn through

(g) A description of the various circles of the sphere, will be found in the explanation of the principal terms made use of in astronomy, given at the end of the work.

the place proposed; and by reckoning how many degrees of that circle are contained between this point and the equator, we are enabled to judge of the situation of the place with respect to its latitude.

Every circle is supposed to be divided into 360 equal parts, called degrees, and every degree into sixty equal parts, called minutes; so that, from these considerations, you will readily perceive what is to be understood by the latitude being expressed in degrees and minutes, and how the distance of any place from the equator may be assigned by them. If, for example, a place is said to have ninety degrees of north latitude, it must, evidently, lie under the north pole; and if it has ninety degrees of south latitude, it must be under the south pole. In like manner, any place which is exactly in the mid-way between the equator and either of the poles, will have forty-five degrees of latitude, north or south, according to the hemisphere in which it lies so that under the equator the latitude is nothing, but increases gradually as you advance towards either of the poles, where it is ninety degrees, or the greatest possible; as will be evident from consulting the above-mentioned figure.

A great number of different places it is obvious, may also have the same latitude; for if a circle be supposed to be drawn through any point of the meridian, parallel to the equator, all the places which lie under that parallel will be equally distant from the equator, and consequently must have the same

latitude; as is the case of the circles 10, 10; 20, 20; &c. It appears, therefore, that by knowing the latitude of a place only, we are not from this alone able to ascertain its exact situation. We can tell under what parallel it lies, or what is its distance from the equator; but other considerations are necessary to fix its precise position in that parallel, and to enable us to find it upon a map or globe.

Before we can do this, we must know the distance of the place from a certain meridian, as well as its distance from the equator. But as none of these circles are, in their own nature, distinguishable from the rest, it will be necessary to fix upon some one in particular, and agree to refer all our computations to that. Suppose, for example, that we take any remarkable place upon the earth, and consider the meridian which passes over it, as the principal one: this may then be called the first meridian, and by noting the points where it cuts the equator, the distance of any place may be properly reckoned from it in degrees and minutes of that circle.

The choice of a first meridian has been a matter of considerable embarrassment both to astronomers and geographers, and even yet they are not perfectly agreed in their determinations. The French formerly made their first meridian pass through the island of Ferro, one of the Canaries; and the Dutch fixed upon another of those islands, called Teneriffe, as the properest situation for this purpose. But the English, with more propriety, make

their first meridian pass over London, or rather over Greenwich, on account of the Royal Observatory being at that place. This disagreement amongst the astronomers of different nations is not, however, to be considered as a matter of much importance; for whichever is regarded as the first meridian, the rest may be easily deduced from it, by noting the different points where they intersect the equator, and finding the difference.

The idea of making the meridian pass over the capital of a kingdom is a very natural one; but you will, no doubt, be curious to know why the islands of Ferro and Teneriffe were fixed upon in preference to all other places for this purpose. The principal reason seems to have been, on account of the westerly situation of these places; for as they lie in the Atlantic ocean, between Europe and America, the first meridian being made to pass over this part of the globe, might then be considered as the western boundary of Europe: besides which, the Dutch and Germans imagine the peak of Teneriffe, on account of its being one of the highest mountains in this part of the world, to be a place peculiarly proper for this purpose.

These reasons, however, are by no means satisfactory. The true position of the Canaries was not, till very lately, determined; and it must surely be injudicious to make the first meridian pass over a place whose situation is but imperfectly. known. Let us, therefore, follow our countrymen, and, without regarding the practice of other nations, refer the longitude of different places to the meri