meter is nearly eight thousand miles, and the perpendicular height of no known hill is much more than three.

To the eye of an observer placed in any part of the indefinite space, where there is nothing to limit his view, all remote objects appear equally distant, and seem to be fixed in a vast concave sphere, of which it is itself the centre. The moon is much nearer than the sun to the inhabitants of the earth; some of the planets are at times nearer, and at other times farther from them than the sun ; others never come so near as the sun always is; the remotest planet in this system is beyond comparison nearer than any of the fixed stars : yet all these ce. lestial objects appear equally distant. If, therefore, we imagine a large hollow sphere of glass to have fixed to its inside as many bright studs as there are visible stars in the heaven, and these studs to be of different magnitudes, and placed at the same angular distances as the stars are placed, that sphere will be a true representation of the heaved, as it appears to an eye supposed to be in its centre, and viewing it all around; and if a small globe, with a map of the earth upon it, be placed on an axis in the centre of this starry sphere, and the sphere be made to turn round on this axis, it will represent the apparent motion of the heavens round the earth.

If a great circle be so drawn upon this sphere as to divide it into two equal parts, or hemispheres, and the plane of the circle be perpendicular to the axis of the sphere, this circle will represent the equinoctial, which divides the heavens into two equal parts, called the northern and the southern hemispheres; and every point of that circle will be equally distant from the poles, or ends of the axis in the sphere: that pole which is in the mid. dle of the northern hemisphere will be called the Horth pole of the sphere; and that which is in the middle of the southern hemisphere the south pole.

If another grand circle be drawn upon the sphere in sucb a manner as to cut the equinoctial at an angle of 23° in two opposite points, it will represent the ecliptic, or circle of the sun's apparent annual motion; one half of which is on the north side of the equinoctial, and the other half on the south. If a large stud be made to move eastward in this ecliptic, in such a manner as to go quite round it in the time that the sphere is turned round westward 366 times upon its axis, this stud will repre. sent the sun, changing his place every 365th part of the ecliptic, and going round westward the same way as the stars do ; but with a motion so much slower than the stars, that they will make 366 revolutions about the axis of the sphere in the time that the sun makes only 365. During one half of these revolutions, the sun will be on the north side of the equinoctial; during the other half on the south ; and, at the end of each half, in the equinoctial.

If the terrestrial globe in this machine were about one inch in diameter, and the diameter of the starry sphere to be about five or six feet, a small in. seet on the globe would see only a very small part of the surface of that body, but it would command a view of one half of the starry sphere, while the convexity of the globe hid the other. If the sphere were turned westward toward the globw, and the

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insect could judge of the appearances which arose from that motion, it would see some stars rising to its view in the eastern side of the sphere, while others were setting on the western. Now, as all the stars are fixed to the sphere, the same stars would always rise in the same points of view on the east side, and set in the same points of view on the west side: but with the sun it would be otherwise, because that luminary is not fixed to any point of the sphere, but moves slowly an oblique circle within it; and should our insect look toward the south, and call that point of the globe, in which the equinoctial seems to cut it on the left side, the east point, and that in which it cuts the globe, on the right side, the west point; the little animal would see the sun rise north of the east, and set north of the west, for 182] revolutions ; after which, he would see it rise south of the east, and set south of the west, for as many more; and, in the whole $65 revolutions, the sun would rise in the east point, and set in the west, only twice. All would be the same, if the starry sphere stood still (the sun pply moving in the ecliptic,) and the earthly globe were turned round the axis of the sphere eastward : for as the insect would be carried round with the globe, its motion would be imperceptible to his senses, and the sun and stars would appear to move westward.

Such are the principles upon which astronomy teaches us to construct the globes, and that more comprehensive machine, the armillary sphere.

GLOW-WORM, see LAMPYRIS.

Glue, among artificers, a viscid matter, which serves as a cement. The common or strong glue is

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made of the skins of animals, and the older the creature, the better is the glue made of its hide, Whole skins are very rarely used, though these are the best for the purpose. Parings, or scraps, and even the sinews of the feet, which last are the worst of materials, commonly supply their place. In making glue of parings, these are boiled to the consistence of a jelly, then strained by means of osier-baskets, poured into flat frames or moulds, cut into square pieces, and dried in the wind.

GLUTEN, a vegetable substance, found in great abundance in wheat, amounting to the twelfth part of the whole substance. It is obtained by kneading the flour into paste, which is to be washed very cautiously, by kneading it under a jet of water, till the water carries off nothing more, but runs off colourless, what remains is gluten: it is ductile and elastic. It has some resemblance to animal tendon or membrane, is very tenacious, and may be used as a cement for broken porcelain vessels. It is the glúten that renders wheat so useful in the art of bread-making.

GNOMES, spirits with which the imagination of certain philosophers has peopled the interior parts of the earth. See the poetical works of the late Dr. Darwin.

GNOMON, in dialling, the style, pin, or cock of a dial, which by its shadow shows the hour of the day. The word is Greek, and literally signifies something that makes a thing known : thus the style makes the bour known.

GNOSTICS, the name of a sect of Christians who were known in the east from the time of the first rise of Christianity. The first gnostics force knopp* ing," or "enlightened” Christians) were Pythagorean or Platonic philosophers, who fancied they discovered deeper mysteries in the Scriptures than were perceived by those whom they considered as simple and ignorant. In process of time, the name designated sectarians of various descriptions, but who all agreed in certain opinions ; and the tenet which seems most particularly to distinguish the gnostic name, was the existence of two first principles, or deities, the one the author of good, and the other of evil.

Jesus Christ they considered as the Son of God, and therefore inferior to the Father. He came into the world, they said, for the rescue and happiness of miserable mortals, oppressed with matter and evil beings. His manhood they denied, on the principle, that every thing corporeal is intrinsically evil.

GOBELINS, or Hotel-Royal de Gobelins, a cele. brated academy for tapestry-drawing, and manu. factory of tapestry, erected in the suburb of St. Marcel, at Paris, by Lewis XIV. in the year 1666. The place was previously famous on account of the dyeing manufactory established there by Giles and John Gobelins, in the reign of Francis I. These eminent dyers discovered a method of producing a beautiful scarlet, which has ever since been known by their name ; and so extensive has been their fame, that not only the colour, but the bouse in which their business was carried on, and the river they made use of, are called Gobelins.

GOD, the supreme being, the first cause, or creator of the Universe, and the only true object of religious worship. God, says sir Isaac Newton, is a relative term, and has respect to servants. It