. which probably arises not only from a diversity in their real size, but from their various distances. On this account they have been divided into several classes hence called magnitudes: thus, those which appear the largest, are called stars of the first magnitude, and are probably nearest to us; next to these are those of the second magnitude, and so on to the sixth which is the last magnitude that can be seen with the naked eye. All beyond these are called telescopic stars, from their requiring a telescope to see them; they are divided into many classes, and, notwithstanding their apparently diminutive size, they do not lose one particle of their importance in the opinion of astro nomers, who by their means have made some great discoveries. 19. There are some of the fixed stars, which though they appear single to the naked eye, yet, when they are examined with a good telescope, are found to consist of two or more stars exceedingly near to each other; these are called Double Stars, &c. There are likewise others. scarcely visible to the naked eye, which from their exhibiting a dim and cloudy light, are called Nebula; when seen through a telescope they appear like dusky specks or clouds. They are supposed to be clusters of stars closely connected in the most beautiful arrangement, and at such an inconceivable distance from our System, that each of them is conjectured to be composed of several thousand distinct luminous bodies. Thus they are similar in their nature to that broad line of light which goes quite round the heavens, and which, from its appearing to be of a milky whiteness, is called the Milky Way, or sometimes the Galaxy, from a Greek expression (yaλažias kúkλoç) having the same signification. There is no doubt but that its whitish appearance arises from the mixed lustre of the numberless stars which compose it, and which, owing to their immense distance from us, appear merely as a luminous cloud. Sir Wm. Herschel has furnished us with a new and gigantic idea concerning the milky way; he supposes the sidereal universe to be divided into clusters or strata of stars, and the milky way to be that particular cluster or stratum in which our sun is placed. Hence we see all the stars towards the extremities of this stratum in the form of a great nebulous circle, which appears lucid on account of the immense accumulations of the stars; whilst the rest of the heavens at the sides seems only to be scattered over with constellations more or less crowded, according to the number of stars contained in the sides of the stratum. 20. The ancients portioned out the firmament into several parts or constellations under the representation of certain images, by way of assisting the memory in distinguishing their disposition and direction. These divisions which appear to have been coeval with the knowledge of astronomy, were probably made by the Egyptians, who used them as signs of the different seasons, and as a directory for commencing the operations of ploughing, sowing and the other labours of husbandry. There are a great many of them, but twelve are rendered more important than the others, by reason of the Orbit, in which the Earth performs its annual period (and which the Sun seems to move round every year), running under the very middle of them: these Constellations, being fancied to represent certain things, are called Signs, and because the things so represented are most of them Zodia (dia) i. e. animals, hence the whole tract is styled the Zodiack, and the figures themselves are called the Signs of the Zodiack. The names of these Signs are Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, The Virgin and the Scales; They are denoted by certain characters which may be seen in Plate I. fig. 1. The middle part of the Zodiack is also called the Ecliptic because all eclipses (ékλɛipεis) can only happen when the planets are either in or near this line. The Greeks, who borrowed their knowledge of astronomy from the Egyptians, retained several of their figures, but accommodated almost all of them to the fabulous history of the gods and heroes, whom they thus placed amongst the stars. But the division of the firmament by the ancients only took in so much of the visible heavens as came under their notice: and hence, as well as from our more extended knowledge of those with which they were acquainted, the number of constellations has been very materially increased. 21. The Egyptians borrowed the names of the constellations from various animals, in which they imagined they found certain qualities connected with the appearances of the sun, moon, and some of the stars. Thus, by the sign Aries or the Ram, a prolific animal, they represented the fertilizing warmth of the sun in the Spring; and by that of Leo or the Lion, a hot and furious beast, they denoted the scorching heat of the sun in Summer: they regarded Taurus or the Bull as a fitting emblem of the sun's power in for warding the operations of agriculture, to which this animal was subservient; and Libra or the Balance was a proper type for that part of the heavens in which the sun appears at one of the equinoxes, when he distributes equal day and night to the whole earth. 22. It was hence, from their having been Signs pointing out the times and seasons of the year, that they came to be considered as the causes of heat and cold, dryness and moisture, and as having dominion not only over the inanimate creation, but over the complexions, constitutions, and dispositions, of Man. From this it was but one step to that opinion, which conceived the Sun, Moon, Planets, and Stars, to be of a divine nature, governed and inhabited by inferior deities of a middle nature between man and the Supreme Being; and the worship which was hence paid to them, appears to have been the origin of all the idolatry which has been practised in the world. This worship is called in the Scriptures the worship of the host of heaven, or in Hebrew Seba Schamaim, from which the moderns have fashioned the names of Sabaism for the worship, and Sabæans for the worshippers themselves. These early idolaters first worshipped the planets as being the nearest of the heavenly bodies to them, and therefore imagined to have the greatest influence on the world; they erected temples to them, and in the absence of the planets worshipped the deities who were thought to govern them, by images, in which, after their consecration, the several influences were thought as much to preside as in the planets themselves. To these images they gave the names of the planets which they represented, and which were ranked the first in the polytheism of the ancients from their being the first of their gods. This religion began among the Chaldæans who communicated it to all the Eastern nations and to the Egyptians; from the latter people it passed to the Greeks who propagated it amongst all the Western nations of the known world. The remainder of this sect still exists in the East under the same name, but their religion is a mixture of Christianity, Judaism, Mahometanism, and Paganism. 23. THE EARTH. We must now return to our own Solar System in order to take a view of the Earth, or that planet which we inhabit. The figure of the Earth is very nearly that of a sphere or globe, which is occasioned by every thing on it being attracted to its centre by the laws of gravitation. A straight line passing through its centre from North to South is called its Axis, in allusion to the (äkwv axis or) axletree of a chariot, because on it the Earth turns round once in twenty-four hours: the extremities of this axis are named the Poles (from nodeiv to turn), and because one of them is always pointing Northward and the other Southward, hence the former is called the North Pole, and the latter the South Pole. The North Pole is likewise called the Arctic, because it points to the constellations of the Great and Little Bears, the Greek word Arctos (apkros) signifying a bear; hence too the Southern Pole is styled the Antarctic, as being opposite (avri) the Arctic. Now it is this daily revolution of the Earth on its axis, which brings us day and night, and which causes us to imagine that the sun, planets, and stars move round it: moreover, this revolution of the Earth being from West to East, hence the heavenly bodies seem to move in an opposite direction, and therefore we say they rise in the East and set in the West. The 24. The roundness of the Earth's figure might have been always observed from the round shadow, which the Earth casts upon the Moon when it eclipses her, and from the observation of the stars, particularly of the Polar Star, which rises as we go North, and sinks as we go South. But it was first proved by the Portuguese navigator Magellan, who com pletely sailed round the Earth at the beginning of the 16th century. appearance of distant objects (especially at sea) as they are approached or lost sight of, also readily shows the rotundity of the Earth's figure, as may be seen in Plate II. fig 1, where the curved line A B represents a part of the surface of the Earth. Thus a person at c will be unable to see the ship at e, because (owing to the curvature of the earth) it is below the visible horizon of his eye; but, as it sails towards him, he will see its topmasts when it gets to the point ƒ, and finally the whole vessel at the point g. 25. It is also by the same laws of gravitation that the Antipodes (from avri against and πódɛç feet) or such inhabitants of the earth as live diametrically opposite to each other, always stand equally upright and firm. For, if we traversed the whole globe, we should every where have the sky over our heads, and our feet towards the centre of the Earth; and our Antipodes may as well imagine that we stand with our heads hanging downwards, as we conceive that this is their pendulous position. Nay farther, we who are now on what we call the uppermost side of the earth, are carried by its revolution in the space of twelve hours to the situation where our antipodes now are, although we shall be as far from them as before. All this is owing to the amazing power of gravitation, the centre of which, so far as regards the inhabitants of the Earth, is the centre of the Earth, and therefore they all gravitate towards this centre: and we must consider the terms up and down merely in relation to bodies being farther from, or nearer to, the centre. This will be rendered more obvious on reference to Plate II. fig. 2. in which A represents the earth, E its centre, and m four little figures upon its surface, whose relative position with respect to the centre must always be the same on whatever part of the earth they may be found. 26. The Diurnal motion of the Earth is illustrated in Plate II. fig 2. where the circle A represents the Earth, the shaded part being that hemisphere which is turned from the sun, and, consequently, in darkness: E is the centre of the Earth, through which (perpendicular to the paper) the Axis is drawn, whereon it makes its daily revolution; f g h i denote the circumference of the heavens, and S the Sun. The Earth being supposed to be thus situated, and to move round its Axis towards the Sun, it is evident, that at the point A the Earth will first begin to be enlightened by the Sun, that is, the sun will there appear to be just rising or ascending the horizon. The Earth having moved round its own axis, so that the point A upon it has come under the point g of the heavens, the Sun will then appear at its greatest height above the horizon for that day, and so it will be noon or mid-day at the place A. The Sun now appears beginning to descend, and when, by the revolution of the Earth, its point A has arrived under the point in the heavens, the Sun will appear to be just setting or sinking be low the horizon. The point A then gets beyond the influence of the Sun and becomes totally darkened; when it comes under i in the heavens, it will be then midnight at it, and when under f, it will be sun-rise again. 27. The term Horizon is derived from a Greek word (opičwv) signifying something that bounds, and hence we use it with respect to the line that beands our view of the earth and heavens. When applied to our view of the earth we call it the sensible horizon, by way of distinguishing it from the rational or real horizon, which would bound our view, if we could see at once half the Globe. The point in the heavens directly over our heads is called the Zenith, and that diametrically opposite below, the Nadir. It is the rational horizon which is represented on globes by the wooden circle which surrounds them. 28. The Diurnal motion of the Earth on its own axis must not be confounded with its Annual revolution in its orbit round the Sun: the former only produces Day and Night, but the latter causes the different lengths of day and night, as well as the phænomena of the Seasons. 29. It is this latter which makes the Sun to appear as if it had such an annual motion round us, and it may be better understood by referring to Plate II. fig. 3. where the Sun is represented in the centre, the orbit of the Earth by the dotted circle next round it, and the Ecliptic with its twelve signs by the outermost circle. Now, supposing the Earth to be at A, the Sun will appear to us to be at Libra; and, supposing the Earth to move from A to B, and so to C, the Sun will thereby appear to us to move from Libra to Scorpio and thence to Sagittarius. In like manner by the Earth's motion along the rest of its orbit till it comes to A again, the Sun will seem to us to move along the rest of the Ecliptic till it once more comes to Libra. Hence it will be observed, that, whereas we commonly say the Sun is in Libra, when it is between us and Libra (and so on of the other signs), we should, properly speaking, say that the Earth is then in Aries, or the sign diametrically opposite to Libra; inasmuch as the Earth is always in that point of the Ecliptic diametrically opposite to the one in which the Sun appears to be. 30. It has been already said that the Diameter on which the Earth turns is called its Axis, the two extremities of which are named its Poles. Between these Poles every point in the Earth does by its Diurnal Rotation describe a circle; and, because all these circles must always keep at the same distance from the Equator or |