TO-MORROW. 'How sweet to the heart is the thought of to-morrow, When Hope's fairy pictures bright colours display! How sweet when we can from futurity borrow A balm for the griefs that afflict us to-day! Let me hope-(oh! how soon would it lessen my anguish)— 'When trav'lling alone, quite forlorn, unbefriended, 'When six days of labour, each other succeeding, 'But th' infidel then sees no joyous to-morrow; Yet he knows that his moments are hasting away: Poor wretch! can he feel, without heart-rending sorrow, The work is neatly printed, and constitutes a pleasing addition to the libraries of all lovers of the muse. INTELLIGENCE, LITERARY, PHILOSOPHICAL, &c. Royal Institution.-Lectures on Geology.-LEC. II. THIS lecture treated of the position and arrangement of Primary Rocks. These rocks, according to Mr. Davy's system, are only six; granite in blocks and stratified, micaceous schist, primitive limestone, serpentine, sienite and porphyry. The other six rocks, which, according to Werner, are primitive, viz. sileceous schist, argiliaceous schist, topaz rock, quartz rock, flinty slate, and primitive gypsum and trap, are classed with secondary rocks, or omitted in this arrangement. For Mr. Davy observed, that he considered all rocks which contained fragments of other rocks to be of secondary formation, as well as those which contain the remains of animals or vegetables. In micaceous and argillaceous schists, Mr. Davy said, he could trace the minute frag ments of other stones. He excluded from the primary mountains those of Wales, Cumberland, and every part of England, except the mountains of Cornwall, Devonshire, Leicestershire, and the Malvern Hills.-Granite, micaceous schist, sienite, serpentine, porphyry, and marble, are primary rocks. All these arrangements are constituted by a few crystalline substances, which are principally quartz, feldspar, mica, hornblende, talc, and calcareous spar. Thus granite is an aggregate of crystal, of quartz, mica, and feldspar; sienite, of quartz, feldspar, and hornblende: micaceous schist, of quartz, and mica; and serpentine, of shiller-spar, talc and feldspar, containing veins of steatite. Mr. Davy's definitions of granite, and the six primary rocks, except serpen tine, agree with the present received system of geologists; but he observed that primitive serpentine is crystallized, like the other primary rocks: in some instances, the crystals are very minute, and scarcely perceptible. His obser vations, relative to the arrangement and position of these rocks, were illustrated by the exhibition of several drawings, representing their general appear ance and position in Cornwall, Ireland, and other parts of Europe. He regretted that granite had not been employed in architecture in this country. Not an obelisk nor column would remain to prove our former greatness; and though London might be a beautiful city one thousand years hence, not one of its present edifices would then be in existence. Mr. Davy observed, that though the genera, and even the species, of primary rocks are few, their varieties are almost infinite. The stones of which they are composed are chiefly quartz, feldspar, mica, hornblende, shiller-spar, talc, and primitive limestone. The earths of which these are composed are still fewer; being only silex, clay, magnesia, and lime; and to these may be added the oxyd of iron, with which most stones are more or less coloured. These substances, variously combined, give rise to the great variety in the forms and appearances of their crystals; and Mr. Davy's late discoveries prove, that the earths and alkalies have metallic bases, and that they are com pounds of these bases and oxygen. To the chemist belong the province of analysing these rocks, and discovering the qualities and proportions of the earths they contain, which he is enabled to do with much accuracy; but when this is done, we are still far from having obtained the simplest forms in which these earths exist: they are still compounds, being all of them metals united with oxygen. The principal difference between the metals of the earths, and those commonly known, is their combustibility: they all inflame or oxydate at the common temperature of the atmosphere. In the arrangement of the primary rocks, a certain order and relationship is generally to be observed. Granite is the highest and the deepest rock; it forms the summit of the loftiest mountains, and seems to be the foundation of our continents and islands, and is usually covered, either by gneiss, (itself a species of granite), micaceous schist, or sienite. Serpentine and marble occupy the middle stations of mountain chains, and are oftener found upon micaceous schists than upon granites. Porphyry is mostly associated with granite, and is frequently immediately incumbent upon it. The primary rocks constitute the principal solid part of the surface of our globe, and form the loftiest mountains, and their geographical position is admirably adapted to preserve the order and economy of the system. The heights of mountains in general diminish from the equator toward the poles. Where, as in Africa, mountains do not occur, there are sandy deserts. Where mountains rise abrupt from the shores of the ocean, the sea near the coast is always deep, as on the coast of Norway; and, from its depth, the mass of water is slowly cooled, and thus prevented from freezing in latitudes near the poles. Mountains are the origin of rivers; they arrest the progress of the winds, they regulate the currents of the atmosphere, and render fertile many regions of the earth, which, without them, would remain arid, uninhabitable deserts. It is in our power to decompose the materials of which primary rocks are formed; but to recompound them, and crystallize their materials, is beyond our skill; nor, in the present state of science, can we even form an idea of the process by which it is effected. Nothing analogous to such a formation can now be traced in nature. In all systems for explaining the formation of primary rocks, a fluid state, either from igneous or aqueous fusion, is assumed; but, Mr. Davy remarked, it is not yet explained, why different chrystals should separate in the same mass. The chrystals produced either from solutions or by slow cooling in artificial or natural operations are uniform, and not of different species, like these of the primary rocks, so that the solution of this grand pro blem, if it be capable of solution, must be gained from the improvement of chemical science. Nature may produce effects by powers which have not as yet been discovered, and her resources should never be estimated by our operations. The New Comet was seen by M. Flangnergues, at Viviers, in France, on the 25th of March. On the 21st of August, the following account was given by M. Bouvard, dated from the Imperial Observatory, August 21:- 'The Comet discovered at Viviers, on the 25th of last March, by M. de Flangnergues, and seen till the end of May, when it ceased to be visible, in consequence of its proximity to the sun, has again appeared this morning in the constellation of the Little Lion; its motion, almost entirely in declination, carries it toward the north, close to the constellation of the Great Bear, where it will then be visible every night, even to the naked eye. This morning, be tween three and four o'clock, I discovered this Comet very near the horizon; its position was nearly that laid down in the elements calculated by M. Burckhardt; and according to my observations, I have determined it as follows:Right ascension, 147 deg. 18 min.; North declination, 32 deg. 53 min.' The following is a letter from Dr. Olbers, of Bremen, to Professor Boden, on the same subject: The Comet which M. Flanguergues discovered on the 25th of March at Viviers, and M. Pons, on the 11th of April at Marseilles, and which was seen on the 20th of May at Paris, will re-appear before the end of August. It will be much more visible then than in the spring. Its greatest brilliancy will be in October, and it may be visible still in December. In September and October it does not quit with us the southern part of the heavens.' The altitude of the new Comet, as seen at Jamaica on the 11th of June, was 18, right ascension 122, and north declination 8. Its apparent progress in 17 days was eight degrees in a north-east direction. In Great Britain, it was observed on the 27th of August, by Mr. Veitch of Inchbony. About-29 minutes past nine at night, I observed a comet in the N. N. W. quarter of the heavens, about five degrees and a half below a star of the third magnitude, in the posterior paw of Ursa Major, marked U, and answering to No. 34, in Flamstead's catalogue. An imaginary line will pass nearly through the centres of Dubhe and Flamstead's 34, and the comet; and another line, drawn from Lyra through Alcor, will mark out the place of the comet on the first line. Its longitude at present will be nearly in the 20th degree of Leo, and nearly 234 degrees of north latitude; it is nearly round, with a dim light brushing out a considerable distance from the edges of its disc. When viewed by a seven-feet telescope of the Newtonian construction, with a magnifying power of 180, it appears to be larger than Jupiter, but not so 04 well well defined. Being near the circle of perpetual apparition, it may be observed nearly the whole night by the naked eye.-Inchbony, Aug. 28.-J. VEITCH.' The following account is by Mr. Firminger, late assistant astronomer at the Royal Observatory, Greenwich. 'Last Monday morning, August 26, as I was looking for the planet Venus before the sun rose, I discovered this Comet. It was about half an hour past three o'clock when I first saw it, which must have been about three quarters of an hour after it rose above the horizon, as it was then not more than 10 or 15 degrees high. The morning was very fine a little before, but was now getting very cloudy, and particularly about the part where the Comet appeared, so that I had but a transitory view of it; but I should conclude from its situation and appearance, it might have been seen 10 days earlier, particularly as I find, from some subsequent observations, its motion is very slow. It now rises soon after two o'clock in the morning, and may be seen in great splendour about three; it bears a very strong twilight, and I have no doubt but that it may be seen in full day light with equatorial instruments. The appearance is so striking, that any person looking toward the north-east part of the horizon at the time I have before mentioned, viz. about three, or a quarter after three o'clock in the morning, cannot fail of seeing it. Yesterday morning, I saw it with my naked eye till 20 minutes past four. It appears as a bright nucleus, surrounded with a large coma, without a tail.' Another account has been published by Mr. Capel Lofft, under date of Troston Hall, near Bury, Suffolk, September the 8th. "This comet, which was observed in Europe in its descent to the sun from the middle nearly of March to the latter end of May last, and in the West Indies on the 1st of June, when it had passed its descending node, and was coming to its perihelion, and which was again observed at the Observatory at Paris, after it had passed its perihelion, and had risen above its ascending node with a right ascension of 147 deg. 18 min. and a north declination of 324 in the constellation of Leo Minor, is now very conspicuous under the square of Ursa Major, whence it seems to be passing in a direction through the square and the tail of Draco and the body of Ursa Minor, near the tail. Its position last night was considerably near to 6, the more southerly of the two lower stars of the square. 'When first seen here, 21st August, ten minutes past eight in the evening, it had the appearance of a large nebula, nearly circular, and of about one degree in extent, with a central light like that of Andromeda, resembled a hazy star of the fourth or fifth magnitude. It had then R. A. 149 or 50 N. D. nearly 36. Cloudy weather prevented its being again seen till the evening of the 5th, when it appeared like a fixed star of about the second magnitude, with a thin pale train of about 4 deg. min. about half past eight; on the 6th it was brighter very considerably: its train then, viewed with a good four-foot and a half refractor of Dolland, and a very good night-glass adapted for use by Nairne and Blunt, was evidently divided by a darkish shade near the farther extremity. It was very conspicuous even to the naked eye. The head, which had appeared like Saturn in his aphelion, now appeared much more round, like Jupiter in his meridian. Last night, with R. A. of about 262, N. D. of about 42, still advancing toward the square, it appeared even brighter than on Friday, the head a yellowish light pretty well defined; the train (which when most apparent was that and the former night about 6 degrees in length and nearly 4 at its farther extremity) a thin, white splendor, like the coyliest part of the milky way. Breadth of the head (including diffused coma), about 40, or about 1-4th or 1-5th of the Moon's apparent diameter. From its slow motion, and the direction of its path, there seems reason to hope that it will be visible three or four months longer. It is a noble confirmation of the Newtonian and Halleian Theory, having been seen so long before, and now after, its perihelion. ‹ Though 'Though less brilliant than the comet of 1807, it is apparently, and I believe really, a larger comet. From observation of both, and of some others, there seems no reason, in general, to suppose any thing noxious or destructive in their forms, but the contrary.' The Comet was seen to the eastward of the Cape of Good Hope, and in the Southern hemisphere, by the fleet lately arrived from China. It first appeared to them about the end of March, or the beginning of April, in lat. 209 S. and long. 809 E. or thereabout, and continued visible until their arrival at St. Helena, in the latter end of May, when it had approached the sun so much as to set before the termination of the twilight. From its position, they inferred, that it must have been as visible here as it was to them. This Comet is pronounced by Mr. Page, of Congleton, to be the same that appeared in 1601, and whose period is 150 years, and not 129 years, as has been generally supposed, and hence expected in 1789, and confounded with the one seen in 1532; but this opinion is controverted by Mr. Lofft. Sept. 10.—The length of the tail is reckoned by some to be between twenty and thirty millions of miles. The observer, to verify or refute this conjecture, will note the star nearest to the Comet, and that at the extremity of the tail. The following is a catalogue of writings extant on the subject of Comets, extracted from Young's Course of Lectures on Natural Philosophy: : Euler on the Effects of Comets. N.C. Lexell on the Comet of 1770. A.P. Calculates that it moves, as Prosperin supposed, in an elliptic orbit, its period about five years and a half, its aphelion a little beyond the orbit of Jupiter. Pingré, Cometographie. 2 vols. Par. 1783. Desguines, S. E. X. 1785. App. 39. Enumerates two or three hundred Comets mentioned by Chinese authors. Maskelyne on the Comet expected in 1788. Ph.Tr. 1786. 420. Halley admitted doubts respecting this Bode. Ac. Berl. 1786, 1787. Kastner's Gedichte. Vermishte Schrif- Miss Herschel and Dr. Herschel on a Olbers on the Comet expected in 1788. Leipz. Mag. 1787. IV. 430. 235. Rudiger |