Hare, 19; Canis Major, the Greater Dog, 31; Canis Minor, the Leffer Dog, 14; Argo navis, the fhip Argo, 64; Hydra, the Water Serpent of Lerna, 60; Crater, the Cup, 31; Corvus, the Crow, 9; Centaurus, the Centaur, 35; Lupus, the Wolf, 24; Ara, the Altar, 9; Corona Auftralis, the Southern Crown, 12; Pifcis Auftralis, the Southern Fish, 24.

The new fouthern constellations, mostly invisible to us who live fo far north, are,

Columba Noachi, Noah's Dove, 10; Robur Carolinum, the Royal Oak, or King Charles's Oak, a name contrived by Halley in memory of the oak which faved Charles II. 10; Grus, the Crane, 13; the Phenix, 13; Indus, the Indian, 12; Pavo, the Peacock, 14; Apus vel Avis Indica, the Bird of Paradise, 11; Apis vel Mufca, the Bee or Fly, 4; the Chamaleon, 10; Triangulum Auftrale, the Southern Triangle, 5; Pifcis Volans, the Flying Fifh, 6; Dorado vel Xiphias, the Sword Fish, 6; Toucan, the American Goofe, 9; Hydrus, the Water Snake, 10.

The new conftellation in the Zodiac is,

Coma Berenices, Berenice's Hair, 43°, near the Lion's tail: and in the northern region, Antinous, near the Eagle.

The constellations made out of the unformed stars by Hevelius are,

The Lynx, 44, between Gemini and Urfa Major; Leo Minor, the Leffer Lion, between Leo and Urfa Major, 53; Afterion et Charas vel Cor Caroli, the Greyhounds, between Urfa Major and Bootes, 25; Cerberus et Ramus, Cerberus and the Branch, in the right hand of Hercules, 4; Vulpecula et Anfer, the Fox and the Goofe, between the Swan and the Eagle, 35; Scutum Sobieski, Sobiefki's Shield, or the Crofs, 7, near Sagittarius; Lacerta, the Lizard, between Pegăfus and Cepheus, 16; Camelopardus, between Caffiopeia and Urfa Major, 58; Monoceros, the Unicorn, 31, near Canis Major, or the Greater Dog; Sextans Urania, the Sextant of Urania, or the fixth part of a circle, 41, near Hydra: To thefe add, Mount Manalus, near the Serpent; Mufca, the Fly, and the leffer Triangle, between Aries and Perfeus.

In the number of ftars annexed to each conftellation, and ufually marked on modern globes, are included a good many visible only with a telescope.

Some of the principal stars have got particular or proper names, as, Sirius, or the Dog Star, the largest and brightest of all the ftars, in the mouth of the Greater Dog; Procyon, in the Leffer Dog; Aldebaran or the Bull's eye; Capella, or

the

the Goat, in the Waggoner; Arcturus, between the legs of Bootes; Caftor and Pollux, two ftars in Gemini; Hadi, the Kids, two stars in Auriga near Capella; So certain clusters of ftars; as, Pleiades or the Seven Stars, in the Bull's neck; Hyades or Sucula, near the Bull's eye, &c.

On most celestial globes or charts the ftars in each conftellation are distinguished by the letters of the Greek and Roman alphabets, which mark them as exactly as proper names; the contrivance of J. Bayer, a 1603. The first letter of the Greek alphabet is affixed to the largest ftar in each conftellation; the fecond letter to the next, and fo on. If there are more ftars in the conftellations than letters in the Greek alphabet, the remainder are marked with the letters of the Roman alphabet.

There is a particular tract in the sky of a whitish colour, which goes round the whole heavens, called Via lactea, the Galaxy or milky way; occafioned, it is thought, by an innumerable multitude of stars placed in it, which are not visible to the naked eye.

Besides the milky way, there are many other parts of the heavens brighter than the reft, called NEBULA; of which very few are perceptible to the naked eye. Of thefe Dr Herschel has given a very large catalogue. Only 103 had been afcer

tained before. This eminent aftronomer has alfo discovered certain luminous points in the heavens, which, from their uniform and vivid light, he calls planetary nebula.

All these nebula are fuppofed to be produced by the blended light of a vast number of small stars, many of which have been discovered by means of the late improvements in telescopes whereby alfo the number of the ftars has been found to be great beyond conception. We may form fome idea of this from the calculation of the same accurate obferver, that in one quarter of an hour there paffed through the field of view of his telescope no less than 116,000 ftars."

Although the fixed stars appear to remain in the same situation with respect to one another, yet many of them are found to undergo particular changes; and fome aftronomers think that all the stars have a certain motion, fimilar to that of the folar fyftem, which their distance prevents us from perceiving.

Some stars known to the ancients are no longer to be seen, while new ones have been discovered. Some stars are found to have a periodical increase and decrease of magnitude. Some new ftars have appeared all at once with furpaffing fplendour, and in a fhort time have entirely disappeared; as that in the time

of Hipparchus, which is faid to have induced him to compofé his catalogue of ftars for the inftruction of future obfervers.

The firft ftar of this kind obferved by the moderns was dif covered in November 1572, and difappeared March 1574. Several others have fince been obferved.

Some stars have been found to disappear and appear again, and that at fixed periods, hence called re-apparent fars. A number of ftars which appear fingle to the naked eye, when viewed through a telescope, are found to confist of two, three, or more stars.

We may form fome conception of the immenfe diftance of the fixed ftars from this confideration; that although the earth in moving round the fun is 190 millions of miles nearer the fixed ftars in one part of its orbit than in the opposite, yet their magnitude and brightness are not in the leaft altered; and the polar ftar, in every part of the earth's orbit, always appears to us in the fame pofition; hence we conclude, that the whole extent of the earth's orbit is but as an imperceptible point in comparison of the diftance of the fixed ftars.

The CELESTIAL GLOBE.

THE celeftial globe is an artificial reprefentation of the heavens, on which the fixed ftars are marked according to their magnitude and fituation. This is not fo juft a reprefentation of the heavens as the terrestrial globe is of the earth; because the ftars are drawn upon a convex sphere, whereas they appear to us in a concave one. So that to have a proper conception of the celeftial globe, we must fuppofe the obferver placed in the centre, and the furface to be tranfparent; then, by turne ing on its axis, it will exhibit a just representation of the appa rent diurnal motion of the heavens.

The planets are not marked on the celestial globe on account of the irregularity of their motion.

The circles on the celeftial are much the fame as on the terrestrial globe.

All circles that divide either globe into two halves are called the great circles of the sphere, of which fome are fixed and immoveable, and therefore marked on the furface of the globe, as the equator (which on the celeftial globe is always called the equinoctial,, and ecliptic; others vary their place or position, according to the fituation of the fpectator; and therefore are

called

called moveable circles, as the horizon and meridian. Such circles as do not divide the globe into two equal parts are called leffer circles; as the parallels of latitude, the tropics, and polar circles.

Great circles paffing through the zenith and nadir, and confequently cutting the horizon at right angles, or ftraight over, are called fecondaries to the horizon; vertical circles or azimuths.

The vertical circle paffing through the east and weft points of the horizon, is called the prime vertical, or circle of east and weft.

The azimuth of any star is an are of the horizon, intercepted between the vertical circle paffing through it, and the north or fouth point of the horizon. Thus, if a vertical circle paffing through a star cut the horizon in a point 70 degrees from the north, we say, the ftar's azimuth is 70 degrees from the north, or 110 degrees from the fouth.

The amplitude of a flar is the distance of its rifing or setting from the east or weft. The amplitude of a star rifing is called ortive or oriental; fetting, occafive or accidental; and both these are called northern or fouthern, as the ftar rifes or fets to the north or fouth of the east and weft points.

Amplitude denotes the bearing of the fun or of a star, with respect to east or weft, only at their rifing or setting; but azimuth fhews their bearing with respect to east and weft at any time, either when above or under the horizon.

All leffer circles parallel to the horizon are called its parallels, and with refpect to the heavens, they are called almacanthers, or parallels of altitude.

The altitude of a ftar, or of any point in the heavens, is an are of a vertical circle intercepted between the ftar or point and the horizon. If the ftar or point be upon the meridian, it is then called the meridian altitude. The complement of altitude, or what it wants of 90 degrees, is called zenith difiance.

The want of vertical circles and parallels of altitude on the globe is fupplied by the quadrant of altitude, which being fcrewed to the brafs meridian in the zenith, and having its lower end put in between the globe and wooden horizon, may be turned about to any point required. The fiducial or graduated edge represents the vertical circles, and the degrees marked on it defcribe the parallels of altitude.

By altering the pofition of the globe, one kind of circles may be made to reprefent or fupply the place of another. Thus, if the poles of the world be brought to the zenith and nadir, that

is, in a parallel fphere, the equinoctial will coincide with the horizon, the meridians will become vertical circles, and the parallels of declination will become alcamanthers, or parallels of altitude. In like manner, if the poles of the ecliptic be brought to the zenith and nadir, the ecliptic will coincide with the horizon, the circles of longitude on the celeftial globe will become vertical circles, and the parallels of latitude will become alcamanthers; for the latitude and longitude of stars are determined from the ecliptic.

The longitude of the ftars and planets is reckoned upon the ecliptic; the numbers beginning at the first point of Aries, or the vernal equinox, where the ecliptic croffes the equator, and increafing according to the order of the figns. Thus, fuppofe the fun to be in the 10th degree of Leo, we fay, his longitude or place is 4 figns, 10 degrees; because he has already paffed the 4 figns, Aries, Taurus, Gemini, Cancer, and is 10 degrees in the fifth.

The latitude of the stars and planets is determined by their distance from the ecliptic, upon a fecondary or great circle paffing through its poles, and croffing it at right angles. Twenty-four of thefe circular lines, which crofs the ecliptic at right angles, 15 degrees from each other, are ufually marked on the celeftial globe, meeting in two points, called the poles of the ecliptic. Hence longitude and latitude on the celestial globe bears just the fame relation to the ecliptic, as they do on the terrestrial globe to the equator.

As the longitude of places on the earth is measured by degrees upon the equator, counting from the first meridian; fo the longitude of the heavenly bodies is measured by degrees upon the ecliptic, counting from the first point of Aries. And as latitude on the earth is measured by degrees upon the meridian, counting from the equator, fo the latitude of the heavenly bodies is measured by degrees upon a circle of longitude, counting either north or fouth from the ecliptic. The fun, therefore, has no latitude, being always in the ecliptic; nor do we ufually speak of his longitude, but of his place in the ecliptic, expreffing it by fuch a degree of fuch a fign, as, 5 degrees of Taurus, inftead of 35 degrees of longitude.

The two points where the ecliptic croffes the equinoctial are called the equinoctial points, and the first points of Cancer and Capricorn the folftitial points. The meridian paffing through the equinoctial points is called the equinoctial colure, through the folftitial points the folftitial colure.

The