sical truth, the value of which it is impossible to overestimate. In the "Cycle of Celestial Objects" by Captain Smith, he will find all the great truths of astronomy, embracing the most recent discoveries, clearly and accurately described, and requiring little or no mathematical knowledge for their comprehension. In the first volume, bearing the forbidding title of Prolegomena, he gives us in three chapters, an "introductory sketch of the progress of astronomy," "a glimpse of the solar system," and " a glance at the sidereal heavens," and concludes it with a chapter "on the details of the observatory," and a fifth, entitled "Notanda on the Bedford Catalogue." These notanda form an introduction to the Bedford Catalogue itself, which occupies the whole of the second volume, and embraces the "Cycle of Celestial Objects," which forms the general title of the work. This Cycle or Catalogue contains a description of eight hundred and fifty celestial objects, including double and multiple stars, of which the primaries are in Piazzi's catalogue, a selection of clusters of stars and nebulæ from the works of Sir William and Sir John Herschel, together with the most interesting of the celestial objects inserted by Messier in the Connaissance des Temps, for 1781. The following list of contents will shew the reader the number of phenomena to which his attention is called.

These various objects are described with such minuteness, that they may be readily found in the heavens, and the observations upon them by different astronomers, both ancient and modern, domestic and foreign, have been collected with singular care, while the account of Captain Smith's own observations and researches relative to many of the objects of the Cycle, gives a character of originality to his descriptions. The fourth chapter of his first volume, entitled, "Details of the Observatory," and containing an account of his own observatory at Bedford, and of the instruments with which it is furnished, cannot fail to be useful to young astronomers, and instructive to all. Throughout the whole of his work, Captain Smith displays a thorough knowledge of his subject, and never omits to associate with the grand phenomena of the heavens, that great Being whose handiwork they shew forth, and whose glory they declare.

In Dr. Nichol's work "On some important points relating to the System of the World," he treats of the material universe under two different aspects, as represented in space and time by the grander phenomena of the heavens and as represented in time

by the evolutions of individual globes, such as the earth which we inhabit. Under the first of these heads, he describes the structure and extent of the sidereal arrangements, and explains the grounds upon which he has modified his former views relating to the constitution of nebulaæ; and he has illustrated this part of his work with beautiful and highly interesting engravings of the more important nebulæ, as given by Sir John and Sir William Herschel, and as more recently exhibited in the great telescope of Lord Rosse. In the second part of his work, he treats of the analogy of the planets with the earth, and of the epochs of evolution through which the earth has passed,—of the subsidence and elevation of seas and continents, and the instructive phenomena of coral reefs, and islands;-and the interesting speculations of M. de Beaumont, respecting the age of mountains, and the different epochs at which the mountain chains of our globe were raised into their present position, are discussed with much ingenuity and eloquence, and illustrated by plates and diagrams, which cannot fail to add to the popularity of the work.

The limits necessarily assigned to this article, will not permit us to follow either, and still less both, of our authors, through the whole range of their discussions, and we must therefore perform the more difficult task of giving a general view of the system of the universe, and of some of the more remarkable phenomena which are displayed in nearly every one of the planetary bodies which it is in our power to explore. In following this plan we shall carefully abstain from all extravagance of speculation, and call the attention of the reader to those facts and phenomena alone which must command universal belief, and to cautious deductions which reason and analogy will not fail to confirm.

The first and grandest object which arrests the heavenward eye is the glorious SUN, the centre and soul of our system, the lamp that lights it, the fire that heats it, the sceptre that guides and controls it, the fountain of colour, which gives its azure to the sky, its verdure to the fields, its rainbow hues to the gay world of flowers, and the "purple light of love" to the marble check of youth and of beauty. This globe of fire is 883,000 miles in diameter, or 1114 times the diameter of our earth, and is 500 times larger than all the planets put together. It seems to consist of a dark nucleus, which is seen through openings in the luminous crust, called the spots in the sun. It is therefore not an incandescent globe, and there is reason to think with M. Arago, that its light is that of burning gas. The light of the sun moves with the velocity of 192,000 miles in a minute. It is composed of three different colours, red, yellow, and blue, by the combination of which all the different colours in nature are pro

duced. The solar light has more blue and less red in it than the artificial white flames with which we are familiar, and what is very remarkable, these artificial white flames contain many specific rays of a determinate refrangibility, which do not exist in the sun's light, from which they have probably been absorbed either in the process of combustion, or during the subsequent passage of the light through the solar atmosphere. The sun revolves round his axis in 25 sidereal days, and occupies a fixed position in reference to the other bodies of the system. Around the sun, and at the distance of 36 millions of miles, the planet MERCURY revolves in nearly 88 days. Its diameter is only 3140 miles, and it revolves about its axis in 24 hours and 5 minutes. The best time for seeing this planet, which exhibits several of the phases of the moon, from a little more than a half moon to a thin crescent, is about one hour and three quarters before sunrise in autumn, and after sunset in spring. Mercury is occasionally seen in the form of a round black spot, passing across the sun's disc, a phenomenon which will occur on the 9th November 1848, the 11th November 1861, and the 4th November 1863. According to Sir William Herschel's observations, the disc of Mercury was always equally luminous, without any dark spot or ragged edge; but M. Schroeter saw not only spots but mountains, the height of two of which he measured, and found one to be about a mile and a quarter in height, and the other about ten miles and three quarters, or nearly thrice as high as Chimborazo. We are not aware that these observations have been confirmed. Captain Smith looked for the spots on Mercury through his achromatic telescopes, but though he did not find them, he should not have omitted, as he has done, all notice of the observations of Schroeter. The telescope of Lord Rosse will soon decide these and other disputed points in astronomy.

Next to Mercury the planet VENUS revolves round the sun at the distance of sixty-eight millions of miles, in 224 days 16 hours, performing her daily revolution about her axis in 23 hours 21 minutes. The diameter of Venus is 7700 miles, or a little less than that of the Earth. This planet is known even to the most illiterate observer, as the splendid morning and evening star, which occasionally precedes the rising, and follows the setting of the Sun. She shines with a peculiar brilliancy, giving a distinct shadow to opaque objects, and she exhibits all the phases of the Moon. Venus was mentioned by the prophet Isaiah as a morning star 2600 years ago, and is also noticed by Homer and Hesiod. Her splendour could not fail to attract popular attention, and being the nearest planet to our Earth, and almost of the same size, astronomers expected to discover analogous resemblances between the two. Sir W. Herschel and Schroe

ter have examined the surface of Venus with peculiar care. Both of them observed that the light is strongest at the outer limb, from which it decreases gradually to the interior edge. Sir W. Herschel saw spots upon the inner margin of the luminous crescent, not very unlike those seen long before by Bianchini. According to Schroeter, the light at the inner margin terminates in a ragged edge, and the cusps or horns of the planet are alternately blunt and sharp, a phenomenon which Schroeter supposes to arise from the shadow of a high mountain. This astronomer, who noticed that one of the cusps was bent like a hook, with a pale blue light at its apex, ascribed the appearance to the twilight produced by the atmosphere of the planet. Schroeter measured the altitude of four mountains in Venus, the highest of which were, as in Mercury, in the southern hemisphere. The highest was 22 miles, the next 19, another 11, and the lowest nearly 11 miles. Judging from analogy, astronomers expected to find a moon or satellite revolving round this planet. Cassini, and Short, and Montaigne, declare positively that they saw it; but, notwithstanding the charge of dogmatism which Captain Smith has made against those who ascribe this observation to an optical illusion, we have no hesitation in repeating that opinion. It is surely more reasonable to believe that a false image of so bright a planet usurped the place of a satellite, than that the star seen by Short and others, and never seen since, had been blotted out of existWe have ourselves been summoned to see the satellite of Venus, and soon detected the origin of the false speck of light.* Venus, like Mercury, occasionally passes, in the form of a dark round spot, over the Sun, but no satellite has ever been seen to attend her on this occasion. Venus will pass over the Sun's disc on the 9th December 1874, and on the 6th December 1882.

ence.

The next body of the Solar System is our own EARTH, our planetary home, our birth-place, and soon to be our grave. Viewing it, as we are now doing, as the third planet in order from the Sun, can we doubt that it is a globe like the rest-poised in ether, and moving round the central luminary? Knowing that it

*

Captain Smith repeats his opinion in a note, as follows:-" Sir David Brewster says that Mr. Wargentin had in his possession a good achromatic telescope, which always shewed Venus with such a satellite, and the deception was discovered by turning the telescope about its axis.' This, however, must be a mere pleasantry, for it is impossible that the accurate observers cited could have been deceived through so gross a neglect."-Note, vol. i., p. 109. To this we reply, that the statement thus challenged is a historical fact, and that it must have been very pleasant to Mr. Wargentin to have discovered the illusion, before he announced the discovery of a satellite to Venus. If the telescope had a stand, the detection of the illusion would have been more difficult. No person who has studied the optical illusions produced in telescopes, can doubt the possibility of the fact.

is the seat of life, and the abode of intelligence, can we doubt that the other planets have their inhabitants as well as ours? The diameter or axis of the Earth, round which it revolves in 24 hours, is 7898 miles, and its equatorial diameter 7924. It moves round the Sun in 365 days, 6 hours, and it is accompanied by a MOON or Satellite, which revolves about her axis in 27 days, 8 hours, the time also of her revolution round the Earth, at the distance of 237,000 miles from our planet. Her diameter is 2160 miles. Her surface is composed of hill and dale, rocks and mountains, but no trace of water exists, and no appearance which indicates the existence of living beings. The grand object of the refulgent lamp of night is doubtless to give light to our globe, and to regulate the tides of our ocean. As our own Earth was long in preparation for the occupation of man, the Moon may in like manner be preparing for the reception of inhabitants. According to Sir W. Herschel, the height of the lunar mountains which he measured varies from a quarter of a mile to a mile and three quarters; but M. Schroeter, following another method of measurement, found the insulated mountains so high as five miles. The surface of the Moon is distinguished from that of our Earth, and, indeed, of all the other planets, by caverns sometimes five miles in depth, and 40 miles in diameter. A high annular ridge, marked with lofty peaks and numerous little cavities, generally surrounds these caverns, and in its centre an insulated mountain is often found. "The strata of mountains," as we have elsewhere observed," and the insulated hills which mark the disc of this luminary, have evidently no analogy with those in our own globe. Her mountainous scenery, however, bears a stronger resemblance to the towering sublimity and the terrific ruggedness of Alpine regions, than to the lower inequalities of less elevated countries. These masses of rock rise at once from the plains, and raise their peaked summits to an immense height in the air, while projecting crags spring from their rugged flanks, and threatening the valleys below, seem to bid defiance to the laws of gravitation. Around the base of these frightful eminences, are strewed numerous loose and unconnected fragments which time seems to have detached from their parent mass, and when we examine the rents and ravines which accompany the overhanging cliffs, we expect every moment that they are to be torn from their base, and that the process of destructive separation which we had contemplated in its effects is about to be exhibited in tremendous reality. The strata of Lunar mountains called the Apennines, which traverse a portion of the moon's disc from north-east to south-west, rise with a precipitous and craggy front from the level of the Mare Imbrium. In some places, their perpendicular elevation is about 4 miles, and though they often descend to a much lower level, they present an