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the real number of the stars may be presumed to be beyond all human calculation or conception, and perhaps beyond the grasp of an angelic comprehension.

In consequence of recent discoveries, we have now the strongest reason to believe, that all the stars in the universe are arranged into clusters, or groups, which astronomers distinguish by the name of Nebula or Starry Systems, each nebula consisting of many thousands of stars. The nearest nebula is that whitish space or zone, which is known by the name of the Milky Way, to which our sun is supposed to belong. It consists of many hundreds of thousands of stars.When Dr. Herschel examined this region, with his powerful telescopes, he found a portion of it only 15 degrees long and 2 broad, which contained fifty thousand stars large enough to be distinctly counted; and he suspected twice as many more, which, for want of sufficient light in his telescope, he saw only now and then. More than two thousand five hundred nebulae have already been observed; and, if each of them contain as many stars as the Milky Way, several hundreds of millions of stars must exist, even within that portion of the heavens which lies open to our observation.

It appears, from numerous observations, that various changes are occasionally taking place in the regions of the stars. Several stars have appeared for a while in the heavens, and then vanished from the sight. Some stars which were known to the ancients, cannot now be discovered; and stars are now distinctly visible, which were to them unknown. A few stars have gradually increased in brilliancy, while others have been constantly diminishing in lustre. Certain stars, to the number of 15, or upwards, are ascertained to have a periodical increase and decrease of their lustre, sometimes appearing like stars of the 1st or 2d magnitude, sometimes diminishing to the size of the 4th or 5th magnitude, and sometimes altogether disappearing to the naked eye. It also appears, that changes are taking place among the nebula-that several nebulæ are formed by the decomposition of larger nebulae, and that many nebulæ of this kind are at present detaching themselves from the nebula of the milky way. These changes seem to indicate, that mighty movements and vast operations are continually going on in the distant regions of creation, under the superin tendence of the Sovereign of the Universe, upon a scale of magnitude and grandeur which overwhelms the human understanding.

To explore, more extensively, the region of the starry firmament; to mark the changes that are taking place; to ascertain all the changeable stars; to determine the periodical variations of their lignt; the revolutions of double and triDle stars; and the motions, and other phenomena peculiar to these great bodies, will furnish

employment for future enlightened generations and will, perhaps, form a part of the studies and investigations of superior intelligences, in a higher sphere of existence, during an indefinite lapse of ages.

If every one of these immense bodies be a Sun, equal or superior to ours, and encircled with a host of planetary worlds, as we have every reason to conclude, (see pp. 11, 31,) how vast must be the extent of creation! how numerous the worlds and beings which exist within its boundless range! and, how great, beyond all human or angelic conception, must be the power and intelligence of that glorious Being, who called this system from nothing into existence, and continually superintends all its movements! The mind is bewildered and confounded when it attempts to dwell on this subject; it feels the narrow limits of its present faculties; it longs for the powers of a seraph, to enable it to take a more expansive flight, into those regions which eye hath not seen;" and, while destitute of these, and chained down to this obscure corner of creation, it can only exclaim, in the language of inspiration," Who can by searching find out God?-Great is our Lord, and of great power; his understanding is infinite!-Great and marvellous are thy works, Lord God Almighty!Who can utter the mighty acts of Jehovah-who can show forth all his praise !"

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After what has been now stated in relation to the leading facts of astronomy, it would be needless to spend time in endeavouring to show its connexion with religion. It will be at once admitted, that all the huge globes of luminous and oqaque matter, to which we have adverted, are the workmanship of Him "who is wonderful in counsel and excellent in working;" and forin a part of the dominions of that august Sovereign, "whose kingdom ruleth over all." And shall it ever be insinuated, that this subject has no relation to the great object of our adoration? and that it is of no importance in our views of the Divinity, whether we conceive his dominions as circumscribed within the limits of little more than 25,000 miles, or as embracing an extent which comprehends innumerable worlds? The objects around us in this sublunary sphere strikingly evince the superintendency, the wisdom, and benevolence of the Creator; but this science demonstrates, beyond all other departments of human knowledge, the grandeur and magnificence of his operations: and raises the mind to sublimer views of his attributes than can be acquired by the contemplation of any other objects. A serious contemplation of the sublime objects which astronomy has explored, must, therefore, have a tendency to inspire us with profound veneration of the eternal Jehovah-to humble us in the dust before his august presence—to excite admiration of his condescensior and grace in the work of redemption-to show us the littleness of

this world, and the insignificancy of those riches and honours to which ambitious men aspire with so much labour and anxiety of mind-to demonstrate the glory and magnificence of God's universal kingdom-to convince us of the infinite Bources of varied felicity which he has in his power to communicate to holy intelligences-to enliven our hopes of the splendours of that "exceeding great and eternal weight of glory" which will burst upon the spirits of good men, when they pass from this region of mortality-and to induce us to aspire with more lively ardour after that heavenly world, where the glories of the Deity and the magnificence of his works will be more clearly unfolded.

If, then, such be the effects which the objects of astronomy have a tendency to produce on a devout and enlightened mind-to call in question the propriety of exhibiting such views in religious publications, or in the course of religious instruction, would be an approach to impiety, and an attempt to cover with a veil the most illustrious visible displays of divine glory. It forms a striking evidence of the depravity of man, as well as of his want of true taste, and of a discernment of what is excellent, that the grandeur of the nocturnal heavens, and the perfections of Deity they proclaim, are beheld with so much apathy and indifference by the bulk of mankind. Though "the heavens declare the glory of God," in the most solemn and impressive language, adapted to the comprehension of every kindred and every tribe, yet "a brutish man knoweth not, neither doth a fool understand this." They can gaze upon these resplendent orbs with as little emotion as the ox that feeds on the grass, or as the horse that drags their carcasses along in their chariots. They have even attempted to ridicule the science of the heavens, to caricature those who have devoted themselves to such studies, and to treat with an indifference, mingled with contempt, the most august productions of Omnipotence. Such persons must be considered as exposing themselves to that divine denunciation "Because they regard not the works of Jehovah, neither consider the operations of his hands, he will destroy them and not build them up." If the structure of the heavens, and the immensity of worlds and beings they contain, were intended by the Creator to adumbrate, in some measure, his invisible perfections, and to produce a sublime and awful impression on all created intelligences, (see pp. 22, 26, 28,) it must imply a high degree of disrespect to the Divinity wilfully to overlook these astonishing scenes of Power and Intelligence. It is not a matter of mere taste or caprice, whether or not we direct our thoughts to such subjects, but an imperative duty to which we are frequently directed in the word of God; the wilful neglect of which, where there is an opportunity of attending to it, must subject us to all that is included in the threatening

now specified, if there be any meaning in language.

That the great body of professed Christians are absolute strangers to the sublime sentiments which a serious contemplation of the heavens inspires, must be owing, in part, to the minds of Christian parents and teachers not having been directed to such subject, or to the views they entertain respecting the relation of such contemplations to the objects of religion. In communicating religious instructions in reference to the attributes of God, the heavens are seldom referred to, except in such a vague and indefinite manner as can produce no deep nor vivid impression on the mind; and many pious persons, whose views have been confined to a narrow range of objects, have been disposed to declaim against such studies, as if they had a tendency to engender pride and self-conceit, and as if they were even dangerous to the interests of religion and piety. How very different were the feelings and the conduct of the sacred writers! They call upon every one of God's intelligent offspring to "stand still, and consider the wondrous works of the Most High ;" and describe the profound emotions of piety which the contemplation of them produced on their own minds; " Lift up your eyes on high and behold! Who hath created these things! The heavens declare the glory of God, and the firmament showeth his handy-work.

When I consider thy heavens, the work of thy fingers, the moon and the stars which thou hast ordained-what is man that thou art mindful of him, and the son of man that thou visitest him! Thou, even thou, art Lord alone; thou hast made heaven, and the heaven of heavens, with all their host; and thou preservest them all; and the hosts of heaven worship thee. All the gods of the nations are idols; but the Lord made the heavens: Honour and Majesty are before him. Jehovah hath prepared his throne in the heavens: and his kingdom ruleth over all. Sing praises unto God, ye kingdoms of the earth, to him that rideth on the heaven of heavens. Ascribe ye power to our God; for his strength is in the heavens. Praise him for his mighty acts, praise him according to his excellent greatness." If we would enter, with spirit, into such elevated strains of piety, we must not content ourselves with a passing and vacant stare at the orbs of heaven, as if they were only so many brilliant studs fixed in the canopy of the sky; but must "consider” them, with fixed attention, in all the lights in which revelation and science have exhibited them to our view, if we wish to praise God for his mighty works, and " according to his excellent greatness." And, for this purpose, the conclusions deduced by those who have devoted themselves to celestial investigations, ought tc be presented to the view of the intelligent Christian, that he may be enabled to "speak of the glory of Jehovah's kingdom, and to talk of his power."

Having, in the preceding sketches, consider ably exceeded the limits originally prescribed for this department of my subject, I am reluctantly compelled to despatch the remaining sciences with a few brief notices.

NATURAL PHILOSOPHY.

The object of Natural Philosophy is, to observe and describe the phenomena of the material universe, with a view to discover their causes, and the laws by which the Almighty directs the movements of all bodies in heaven and on earth. It embraces an investigation of the laws of gravitation, by which the planets are directed in their motions-the laws by which water, air, light, and heat are regulated, and the effects they produce in the various states in which they operate the nature of colours, sounds, electricity, galvanism, and magnetism, and the laws of their operation-the causes which operate in the production of thunder, lightning, luminous and fiery meteors, hail, rain, snow, dew, and other atmospherical phenomena. In short, it embraces all the objects of Natural History formerly alluded to, with a view to ascertain the causes of their varied appearances, and the principles that operate in the changes to which they are subject; or, in other words, the laws by which the diversified phenomena of universal nature are produced and regulated. One subordinate use of the knowledge derived from this science, is, to enable us to construct all those mechanical engines which facilitate human labour, and increase the comforts of mankind, and all those instruments which tend to enlarge our views of the operations of nature. A still higher and nobler use to which philosophy is subservient, is, to demonstrate the wisdom and intelligence of the Great First Cause of all things, and to enlarge our conceptions of the admirable contrivance and design which appear in the different departments of universal nature. In this view, it may be considered as forming a branch of Natural Theology, or, in other words, a branch of the religion of angels, and of all other holy intelligences. This department of Natural Science has generally been divided into the following branches: I. Mechanics.-This branch, considered in its most extensive range, includes an investigation of the general properties of matter; such as solidity, extension, divisibility, motion, attraction, and repulsion-the laws of gravitation, and of central forces, as they appear to operate in the motions of the celestial bodies, and on the surface of our globe, in the phenomena of falling bodies, the motions of projectiles, the vibration of pendulums, &c.-the theory of machines, the principles on which their energy depends; the properties of the mechanical powers-the lever, the wheel and axle, the pulley, the inclined plane, the wedge, and the screw-and the effects resulting from their various combinations. From the

investigations of philosophers on these subjects, we learn the laws by which the great bodies of the universe are directed in their motions; the Jaws which bind together the different portions of matter on the surface of the earth, and which regulate the motions of animal, vegetable, and inanimate nature; and the principles on which cranes, mills, wheel-carriages, pile-engines, threshing-machines, and other engines, are constructed; by means of which, man has been enabled to accomplish operations far beyond the limits of his own physical powers.

Without a knowledge of the laws of motion, and assistance from the combined effects of the mechanical powers, man would be a very limited being, his enjoyments would be few, and his active energies confined within a very narrow range. In a savage state, ignorant of manufac tures, agriculture, architecture, navigation, and the other arts which depend upon mechanical combinations, he is exposed, without shelter, to the inclemencies of the season; he is unable to transport himself beyond seas and oceans, to visit other climes and other tribes of his fellow men; he exists in the desert, comfortless and unimproved; the fertile soil, over which he roams, is covered with thorns, and briers, and thickets, for the haunt of beasts of prey; his enjoyments are little superior to those of the lion, the hyena, and the elephant, while he is much their inferior in point of agility and physical strength. But when philosophy has once demonstrated the principles of mechanics, and introduced the practice of the useful arts, "the wilderness and the solitary place are made glad, and the desert rejoices and blossoms as the rose." Cities are founded, and gradually rise to opulence and splendour; palaces and temples are erected; the damp cavern and the rush-built hut are exchanged for the warm and comfortable apartments of a substantial mansion; ships are built, and navigated across the ocean; the treasures of one country are conveyed to another, an intercourse is carried on between the most

distant tribes of mankind; commerce flourishes, and machinery of all kinds is erected, for facilitating human labour, and promoting the enjoy ments of man. And when the principles and the practice of "pure and undefiled religion" accompany these physical and mechanical operations, love and affection diffuse their benign influence; the prospect brightens as years roll on, and man advances with pleasure and improvement to the scene of his high destination.

II. Hydrostatics treats of the pressure and equi librium of fluids. From the experiments which have been made in this branch of philosophy, the following important principles, among many others have been deduced:

(1.) That the surface of all waters which have a communication, whilst they are at rest, will be perfectly level. This principle will be more

clearly understood by an inspection of the follow ing figures. If water be poured into the tube A,

(Fig. 1.) it will run through the horizonta. tube E, and rise in the opposite tube B, to the same

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Aright a. which it stands at A. It is on this Drinciple that water is now conveyed under ground, through conduit pipes, and made to rise to the level of the fountain whence it is drawn. The city of Edinburgh, a considerable part of which is elevated above the level of the surrounding country, is supplied with water from a reservoir on the Pentland hills, several miles distant. The water is conveyed in leaden pipes down the declivity of the hill, along the interjacent plain, and up to the entrance of the castle, whence it is distributed to all parts of the city. If the point A represent the level of the reservoir, C D will represent the plain along which the water is conveyed, and B the elevation to which it rises on the castle hill. On the same principle, and in a similar manner, the city of London is supplied with water from the water-works at London bridge. Had the ancients been acquainted with this simple but important principle, it would have saved them the labour and expense of rearing those stupendous works of art, the aqueducts, which consisted of numerous arches of a vast size, and sometimes piled one above another.

Fig. 2. represents the syphon, the action of which depends upon the pressure of the atmosphere. If this instrument be filled with water, or any other liquid, and the shorter leg, G, plunged to the bottom of a cask, or other vessel, containing the same liquid, the water will run out at the longer leg, F, till the vessel be emptied, in consequence of the atmospheric pressure upon the surface of the liquid. On this principle, water may be conveyed over a rising ground to any distance, provided the perpendicular height of the syphon above the surface of the water in the fountain does not exceed 32 or 33 feet. On the same principle are constructed the fountain

at command, the cup of Tantalus, and other en tertaining devices. The same principle, too, enables us to account for springs which are sometimes found on the tops of mountains, and for the phenomena of intermitting springs, or those which flow and stop by regular alternations.

(2.) Any quantity of fluid, however small, may be made to counterpoise any quantity, however large. This is what has generally been termed the Hydrostatical Paradox; and from this princi ple it follows, that a given quantity of water may exert a force several hundred times greater of less, according to the manner in which it is em ployed. This force depends on the height of the column of water, independent of its quantity; for its pressure depends on its perpendicular height. By means of water conveyed through a very small perpendicular tube, of great length, a very strong hogshead has been burst to pieces, and the water scattered about with incredible force. On this principle, the hydrostatic press, and other engines of immense power, have been constructed.

(3.) Every body which is heavier than water, or which sinks in it, displaces so much of the water as is equal to the bulk of the body immersed in the

water.

On this principle, the specific gravities, or comparative weight, of all bodies are determined. It appears to have been first ascertained by Archimedes, and, by means of it, he determined that the golden crown of the king of Syracuse had been adulterated by the workmen. From this principle we learn, among many other things, the specific gravity of the human body; and that four pounds of cork will preserve a person weighing 135 pounds from sinking, so that he may remain with his head completely above water.

Hydraulics, which has sometimes been treated as a distinct department of mechanical philosophy, may be considered as a branch of hydrostatics. It teaches us what relates to the motion of Auids, and how to estimate their velocity and force. On the principles of this science, all machines worked by water are constructed-as steam-engines, water-mills, common and forcing pumps, syphons, fountains, and fire-engines.

III. Pneumatics.-This branch of philosophy treats of the nature and properties of the atmosphere, and of their effects on solid and fluid bodies. From this science we learn, that air has weight, and presses on all sides, like other fluids; that the pressure of the atmosphere upon the top of a mountain is less than on a plain beneath; that it presses upon our bodies with a weight of several thousand pounds more at one time than at another; that air can be compressed into forty thousand times less space than it naturally occupies; that it is of an elastic or expansive nature, and that the force of its spring is equal to its weight; that its elasticity is increased by heat; that it is necessary to the production of sound, the support of flame and animal life, and the germination and growth of all kinds of vegetables. These positions are proved and illustrated by such experiments as the following:-The general pressure of the atmosphere is proved by such experiments as those detailed in No. II. of the Appendix. The following experiment proves that air is compressible. If a glass tube, open at one end, and closed at the other, be plunged, with the open end downwards, into a tumbler of water, the water will rise a little way in the tube; which shows, that the air which filled the tube is compressed by the water into a smaller space. The elasticity of air is proved by tying up a oladder, with a very small quantity of air within it, and putting it under the receiver of an airpump, when it will be seen gradually to inflate, till it becomes of its full size. A similar effect would take place, by carrying the bladder to the higher regions of the atmosphere. On the compression and elasticity of the air, depends the construction of that dangerous and destructive instrument, the air-gun.

That it is capable of being rarified by heat, is proved by holding to the fire a half-blown bladder, tightly tied at the neck, when it will dilate to nearly its full size; and if either a full-blown bladder, or a thin glass bubble filled with air is held to a strong fire, it will burst. The elasticity of the air is such, that Mr. Boyle, by means of an air-pump, caused it to dilate till it occupied fourteen thousand times the space that it usually does. That air is necessary to sound, flame, animal and vegetable life, is proved by the following experiments: When the receiver of an air-pump is exhausted of its air, a cat, a mouse, or a bird, placed in it, expires in a few moments,

in the greatest agonies. A bell rung in the same situation produces no scund; and a lighted candl is instantly extinguished. Similar experiments prove that air is necessary for the flight of birde the ascent of smoke and vapours, the explosion of gunpowder, and the growth of plants; and that all bodies descend equally swift in a place void of air; a guinea and a feather being found to fall to the bottom of an exhausted receiver al the same instant.

On the principles which this science has established, have been constructed the air-pump, the barometer, the thermometer, the diving-bell, the hygrometer, the condenser, and various other instruments, which have contributed to the comfort of human life, and to the enlargement of our knowledge of the constitution of nature.

IV. Acoustics.-This science treats of the nature, the phenomena, and the laws of souna, and the theory of musical concord and harmony. From the experiments which have been made on this subject, we learn, that air is essential to the production of sound; that it arises from vibrations in the air, communicated to it by vibrations of the sounding body; that these vibrations, or aerial pulses, are propagated all around in a spherical undulatory manner; that their density decreases, as the squares of the distances from the sounding body increase; that they are propagated together in great numbers from different bodies, without disturbance or confusion, as is evident from concerts of musical instruments; that water, timber, and flannel, are also good conductors of sound; that sound travels at the rate of 1142 feet in a second, or about thirteen miles in a minute; that the softest whisper flies as fast as the loudest thunder; and that the utmost limits, within which the loudest sounds produced by artificial means can be heard, is 180 or 200 miles;* that sound striking against an obstacle, as the wall of a house, may, like light, be reflected, and produce another sound, which is called an echo; and that, after it has been reflected from several places, it may be collected into one point or focus, where it will be more audible than in any other place. On these principles, whispering galleries, speaking trumpets, and other acoustic instruments, are constructed.

V. Optics.-This branch of philosophy treats of vision, light, and colours, and of the various phenomena of visible objects produced by the rays of light, reflected from mirrors, or trans mitted through lenses. From this science we

In the war between England and Holland, in 1672, the noise of the guns was heard in those parts of Wales which were estimated to be two hundred miles distant from the scene of action. But the sounds produced by volcanoes have been heard at a much greater distance; some instances of which are stated in Chap. IV. Sect. 2. Several other facta in relation to sound are detailed in Chap. Ul. An Acoustic Tunnels.

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