that this instrument was completed. He had already discovered the planet Uranus, as we related in our last paper; a circumstance, such as had never taken place since the days of the most ancient nations of the world. Moreover, by the aid of the new telescope, Herschel distinguished, one by one, six luminaries revolving about it; as also the seventh satellite of Saturn. The same able astronomer also discovered that the ring which surrounds the planet Saturn, is not only divided into concentric belts by a dark circle, as had been already noticed by Cassini, but that the ring likewise revolved about the body of the planet.

The art of constructing telescopes, has, like all other arts, advanced by degrees to its present state of comparative perfection. In the case of the reflecting telescope, which is, for astronomical purposes, a vast and efficacious improvement upon the former mode of using these instruments, there have been several sorts at different times constructed. These go by the names of the Newtonian, the Gregorian, the Cassegrainian, Brewster's, and Herschel's. The principle of them all is the same: but the circumstances, in which they differ from one another, are chiefly in the manner in which the image of an object is conveyed to the eye of an observer. In every instance, rays of light from the celestial body, pass into the tube of the telescope which is open at the end nearest to the object, and fall upon the surface of the speculum at the bottom of the tube, as shown in the preceding figure. These rays, after reflection from the surface of the speculum, meet again in a focus near the upper end of the tube, and there form a small image of the object; which image is conveyed to the eye of the observer by one of the five different contrivances, which thus form the points of difference between the various reflecting telescopes.

Of Herschel's telescope we have already spoken. Into the merits of the telescopes of Gregory, Cassegrain, and Brewster, it is not necessary here to enter: but we cannot refrain from giving a few brief notices of Newton's genius as developed in the construction of a reflecting telescope, for exploring those celestial tracts, which his skill and perspicacity were employed in reducing to order and harmony, for the better understanding of those who were to come after him.

It has been well remarked of Sir Isaac Newton, that it was his brilliant fortune to improve almost every subject to which he directed his gigantic mind. He was the first to put in practice the idea of employing reflected light for the formation of the image in a telescope. Vast and splendid as were the theoretical and mathematical powers of his mind, yet he did not disdain to construct with his own hands the instrument which his inductive reasoning told him would serve the purpose of a telescope. He, accordingly, made the first reflecting telescope which the world ever saw, and which is now in the museum of the Royal Society of London:-a precious memento of the ingenuity of one whose name will never die.

We are told that Newton's first reflecting telescope was 6 inches long, and had an aperture of about 1 inches. The eye-glass was inserted in the side of the tube, and was one-sixth of an inch deep. This instrument, although so small, magnified thirty-five times, and enabled Newton to see the crescent-form of Venus, and Jupiter's satellites. He then made another, which was 2 inches in diameter, and therefore gave a larger reflecting surface to the speculum at the bottom of the tube.

The following figure shows the construction of the Newtonian reflecting telescope.

of curvature, that the rays r d, rd, from any celestial object, will, after reflection, be conveyed to a focus at e, near the mouth of the tube. But, before they reach this point, their progress is arrested by a plane mirror, c, so placed as to make an angle of 45° both with the length and with the diameter of the tube. This plane mirror is held in its place by an arm or bracket, g, fitted to the side of the tube, but at the same time capable of sliding along it, in order that the distance between the two reflectors may be increased or diminished at pleasure. Let us now suppose that rays from a celestial object are entering the tube, and that they are reflected from the surface of the speculum A: instead of meeting at e, they are reflected a second time, from the small plane mirror c, and cross each other at the point f at which point of intersection an image of the object is formed. At this point of the process is the following adaptation a convex lens is fitted into a socket h, the focal power of which lens is such, that the image is in that focus, and the magnitude of the image is increased.

Many disadvantages resulted from the necessity of the observer looking in at the side of the tube; and inconvenience manifestly results from looking down the mouth of the tube. Those who have attempted to construct reflecting telescopes, have always had in view the removal or diminution of the difficulties mentioned before. Complete success, without loss of light, has not, however, attended their efforts. From the time when Galileo made his telescope, which was of the common refracting sort, with eye-pieces, one at each end of a tube, to the construction of Herschel's great reflecting telescope, a period of nearly 200 years, the knowledge of the heavens rapidly progressed. The construction of the Newtonian telescope was an event mid-way; but the further extent of our knowledge of "the argent fields above," will have to depend mainly on the further improvement of our telescopes.

In concluding the subject of ASTRONOMY, we cannot do better than use the thoughtful and eloquent words of Chalmers:

“The first thing which strikes a scientific observer of the fixed stars, is their immeasurable distance. If the whole planetary system were lighted up into a globe of fire, it would exceed, by many millions of times, the magnitude of this world, and yet only appear a small lucid point from the nearest of them. If a body were projected from the sun, with the velocity of a cannon-ball, it would take hundreds of thousands of years before it described that mighty interval which separates the nearest of the fixed stars from our sun and from our system. If this earth, which moves at more than the inconceivable velocity of a million and a half miles a day, were to be hurried from its orbit, and to take the same rapid flight over this immense tract, it would not have arrived at the termination of its journey after taking all the time which has elapsed since the creation of the world. These are great numbers, and great calculations; and the mind feels its own impotency in attempting to grasp them. We can state them in words. We can exhibit them in figures. We can demonstrate them by the powers of a most rigid and infallible geometry. But, no human fancy can summon up a lively or an adequate conception-can roam in its ideal flight over this immeasurable largenesscan take in this mighty space in all its grandeur, and in all its immensity-can sweep the outer boundaries of such a creation-or lift itself up to the majesty of that great and invisible arm on which all is suspended.

But what can those stars be which are seated so far beyond the limits of our planetary system! They must be masses of immense magnitude, or they could not be seen at the distance of place which they occupy. The light which they give must proceed from themselves; for the feeble reflection of light from some other quarter, would not carry through such mighty tracts to the eye of an observer. Å body may be visible in two ways. It may be visible from its own light, as the flame of a candle, or the brightness of a fire, or the brilliancy of yonder glorious sun, which lightens all below, and is the lamp of the world. Or it may be visible from the light which falls upon it, as the body which receives its light from a taper, or the whole assemblage of objects on the surface of the earth, which appear only when the light of day rests upon them-or the moon, which, in that part of it that is towards the sun, gives out a silvery whiteness to the eye of the observer, while the other part forms a black and invisible space in the firmament-or as the planets, which shine only because the sun shines upon them; and which, each of them, present the appearance of a dark spot on the side that is turned away from it. Now

apply this question to the fixed stars. Are they luminous of themselves, or do they derive their light from the sun, like the bodies of our planetary system? Think of their immense distance, and the solution of this question becomes evident. The sun, like any other body, must dwindle into a less apparent magnitude as you retire from it. At the prodigious distance even of the very nearest of the fixed stars, it must have shrunk into a small indivisible point. In short, it must have become a star itself, and could shed no more light than a single individual of those glimmering myriads, the whole assemblage of which cannot dissipate, and can scarcely alleviate, the midnight darkness of our world. These stars are visible, not because the sun shines upon them, but because they shine of themselves, because they are so many luminous bodies scattered over the tracts of immensity; in a word, because they are so many suns, each throned in centre of his own dominions, and pouring a flood of light over his own portion of these unlimitable regions. "At such an immense distance for observation, it is not to be supposed that we can collect many points of resemblance between the fixed stars and the solar star, which forms the centre of our planetary system. There is one point of resemblance, however, which has not escaped the penetration of our astronomers. We know that our sun turns round upon himself in a regular period of time. We also know that there are dark spots scattered over his surface, which, though invisible to the naked eye, are perfectly noticeable by our instruments. If these spots existed in greater quantity upon one side than upon another, it would have the general effect of making that side darker; and the revolution of the sun must, in such a case, give us a brighter and a fainter side, by regular alternations. Now, there are some of the fixed stars which present this appearance. They present us with periodical variations of light. From the splendour of a star of the first or second magnitude, they fade away into some of the inferior magnitudes; and one, by becoming invisible, might give reason to apprehend that we had lost him altogether; but we can still recognise him by the telescope, till at length he reappears in his own place, and, after a regular lapse of so many days and hours, recovers his original brightness. Now, the fair inference from this is, that the fixed stars, as they resemble our sun, in being so many luminous masses, of immense magnitude, they resemble him in this also, that each of them turns round upon his own axis; so that, if any of them should have an inequality in the brightness of their sides, this revolution is rendered evident, by the regular variations in the degree of light which it undergoes.

"Shall we say, then, of these vast luminaries, that they were created in vain? Were they called into existence for no other purpose than to throw a tide of useless splendour over the solitudes of immensity? Our sun is only one of those luminaries, and we know that he has worlds in his train. Why should we strip the rest of this princely attendance? Why may not each of them be the centre of his own system, and give light to his own worlds? It is true that we see them not; but could the eye of man take its flight into those distant regions, it would lose sight of our little world before it reached the outer limits of our system the greater planets would disappear in their turn-before it had described a small portion of that abyss which separates us from the fixed stars, the sun would decline into a little spot, and all its splendid retinue of worlds be lost in the obscurity of distance-he would at last shrink into a small indivisible atom, and all that could be seen of this magnificent system, would be reduced to the glimmering of a little star. Why resist any longer the grand and interesting conclusion? Each of these stars may be the token of a system as vast and as splendid as the one which we inhabit. Worlds roll in these distant regions; and these worlds must be the mansions of life and of intelligence. In yon gilded canopy of heaven, we see the broad aspect of the universe, where each shining point presents us with a sun, and each sun with a system of worlds-where the Divinity reigns in all the grandeur of His attributes-where He peoples immensity with His wonders; and travels in the greatness of His strength through the dominions of one vast and unlimited monarchy.

"The contemplation has no limits. If we ask the number of suns and of systems, the unassisted eye of man can take in a thousand, and the best telescope which the genius of man has constructed, can take in eighty millions. But why subject the dominions of the universe to the eye of man, or to the powers of his genius? Fancy may take its flight far beyond the ken of eye or of telescope. It may expatiate in the outer regions of all that is visible-and shall we have the boldness to say, that there is nothing there?-that the wonders of the Almighty are at an end, because we can no longer trace His footsteps?-that His omnipotence is exhausted because human art can no longer follow him?—that the creative energy of God has sunk into repose, because the imagination is enfeebled by the magnitude of its efforts, and can keep no longer on the wing through those mighty tracts, which shoot far beyond what eye hath seen, or the heart of man hath conceived: which sweep endlessly along, and merge into an awful and mysterious infinity.

that from Altdorf to the St. Gothard, is formed in the same manner along the steep declivities and acclivities, sometimes laid on arches, and sometimes carried over bridges thrown across tremendous precipices. It is paved with flat pieces of granite, so smooth and slippery that the horses would have perpetually stumbled, had they not been rough shod. In some places this road ran along the bare and rugged ridges; in others, down steps either cut in the rock, or formed by large stones, so that for several paces it resembled a staircase. The whole surface of the valley was thickly strewed with vast fragments of rock, while those which still hung on the sides of the mountains seemed threatening to overwhelm us,-the river, during the whole way, thundering along in a continual fall. This valley exhibits the same kind of scenes to which we have long been accustomed, except that the Aar rushes with more impetuous rage even than the Rhone or the Reuss, and is frequently so swelled with torrents as to ravage all the adjacent country: we saw many traces of these terrible devastations. We crossed it in several places, over stone bridges of a single arch, one of which equalled in the length of its span and the dreariness of its landscape, the "Devil's Bridge," in the valley of Schoellenen. About three leagues from Spital we had a glimpse, through the trees, of the Aar falling from a considerable height. In order to gain a nearer view, we climbed along the sides of a steep rock well covered with moss; I leaned against a tree that impended over the precipice, and saw the river rushing from the rock, and spreading into a kind of semicircular expansion in its descent. It fell with fury into a deep and narrow gulf, and then lost itself in the depth of the forest. The body of water was very considerable, and its perpendicular fall at least one hundred and fifty feet. The scenery was also solemnly majestic; the gray rocks on each side rising perpendicularly, and totally bare, except their tops, which were fringed with pines.

Mr. Inglis informs us that throughout Aargau, farming out land is unknown, with the exception of gardens near the large towns. The properties of those who are considered respectable Swiss peasants (for all proprietors who are not noble are called peasants), run from ten up to forty, or at most fifty acres; and good land is considered to yield ten per cent. profit. Many of the peasants have amassed considerable fortunes: but accession of fortune is never made apparent in their mode of living. From 1007. to 3007. per annum is the usual range of expenditure for persons living in what we should call easy circumstances; and it is asserted that not a single individual in the whole of Switzerland spends one thousand pounds per annum. Transference of land is not usual in Aargau; but when it is brought to the market, thirty-six thousand square feet of good land will bring about fifty pounds sterling. All land pays one-tenth part of the produce to government in

the name of taxes.

Aargau is now one of the confederate states of Switzerland, but it belonged formerly to Berne, Zurich, and Baden, and has only been independent since the year 1798. We have stated that the inhabitants consist of Catholics and Protestants in nearly equal numbers; and from this circumstance arises a law, by which its supreme council must consist of members of both religions in equal proportions.

STRENGTH OF HUMAN MUSCLES.

ROBERT FRANÇOIS DAMIENS, who attempted the assassination of Louis the Fifteenth, in 1757, after suffering the most unheard of tortures, was sentenced to be drawn in quarters by four horses. But although they exerted their entire strength, by drawing in four directions upon his limbs, for fifty minutes, the muscles were not torn from their attachments; and being still alive, the executioners were obliged to cut the tendons with a knife, in order to answer the law, which was that the criminal's body should be drawn in quarters. Precisely the same course was resorted to in the case of Ravaillac, who assassinated Henry the Fourth, the horses being unable to dismember the criminal's body.

LUMINOUS APPEARANCE OF THE SEA. II.

THERE are, as has been shown, many varieties of the Medusa enumerated, as possessing the property of lumination. I shall, however, confine myself to a notice of some of the most remarkable which inhabit the North American seas. The most common of these are the Medusa pellucens of Sir Joseph Banks, one of the varieties of which is frequently met with in Boston harbour, and is known by the name of sun-fish,-and the Medusa noctiluca of Forskal, which is about three inches in diameter, and in figure like a mushroom. These last are found in great numbers about the banks which border the American coasts, and their presence may be regarded as an indication of the approach to soundings. They are of a brownish colour, and have tentacula, like the M. pellucens, but thicker and shorter. Their margin is fringed in the same manner, to the depth of about three-eighths of an inch, and, together with the rays or ribs, resembles a wheel of light, which enlarges or diminishes, as the animal contracts or expands itself.

The former of these, the M. pellucens, is of an hemispherical form, and ordinarily about five inches in diameter, and the summit of the crown is marked by a circle about an inch and a half in diameter. This is divided into six equal compartments, by the intersection of three dark lines; and from the circumference of this circle to the margin of the animal, proceed a great number of radiations, of a purple or brown shade. The border is fringed by a small threadlike membrane, in the form of scallops, not unlike the gills of fishes, and perhaps answering a similar purpose. From this depend a great number of long tentacula, or feelers, which probably serve the purpose of securing their prey, by entangling it in their folds. From the centre of the interior is suspended a kind of bag, terminating in four or five finger-like points, which appear to be the stomach and viscera. lustre proceeds chiefly from the crown and margin.

The

This creature's light is extremely brilliant, and the flashes are frequently so vivid as painfully to affect the eyes of one who looks at them for any length of time steadily. I have known the water to be so filled with them on the American coasts, after the prevalence of an easterly storm, that it was dangerous to run for the land in the night, owing to the difficulty of distinguishing the lights on the shore, from those in the water which were flashing round us in every direction. At another time, in a heavy gale from the N. E., in latitude 35°, between the Gulf-stream and soundings, I witnessed one of the most magnificent, yet awful scenes, that can be imagined. The night was very dark, with frequent lightning in the western quarter, but until about eleven o'clock, nothing unusual was About that observable in the appearance of the sea. time it began to grow luminous, and by midnight the spectacle was sublime beyond description. The lightning appeared to mingle with, and career along a waste of fire; and each successive shower of spray enveloped hull, and cordage, and canvass, in a sheet of lurid light. The extremities of the spars were glittering with luminous points, and the plies of the rigging were gemmed in the same manner: as these were driven from one place to another by the wind, they presented the appearance of sparks from a forge. The effect of the light on the countenance was unpleasant in the extreme, and even appalling. The faces of the crew had a distorted and unnatural air, and wore a green and ghastly look, similar to that sometimes produced on the stage in incantation-scenes.

The