ASTRONOMICAL DISCOVERIES*. THE HE discoveries and progress of the Astronomical Science in the three years that have elapsed since the publication of the volume of the ANNUAL REGISTER for the year 1847, have been neither few nor unimportant. During that period five new PLANETS have been added to our system. The first of these was discovered by Mr. A. Graham, director of Mr. Cooper's Observatory, Mackree Castle, on the 26th April, 1848. The discovery was due, not to any fortuitous detection, but to the steady prosecution of a search for planets in this region of the heavens, which had been for some time followed up. The new body received the name of "Metis" (Counsel, on account of its discovery having resulted from a plan of observation previously devised by Mr. Cooper), with an eye and star for its symbol. Metis is another of the singular group of planets between Mars and Jupiter, in which Astraa, Hebe, Iris, and Flora have been added within a few years, beside the more familiar names of Ceres, Juno, Pallas, and Vesta; the period of revolution is 1346 days, or almost identical with that of Iris; and its orbit approaches very nearly to those of Vesta and Flora. It is not brighter A summary of the progress of Astronomical Discovery, and especially of the discovery of Neptune by Messrs. Le Verrier and Adams will be found in the ANNUAL REGISTER, 1846, p. 455; continued in the volume for 1847, p. 376. than a star of the 9-10th magnitude. On the 12th April, 1849, M. de Gasparis, of the observatory of Naples, discovered a planet of the 9-10th magnitude, to which the name of Hygeia Borbonica has been given, with a serpent crowned with a star for its symbol. Its period of revolution is 2014-7 mean solar days. It was found in that formerly vacant interval between Mars and Jupiter, now peopled by so many of these small bodies. "It seems destined," says the Notices of the Astronomical Society, from which these accounts are derived," that our ideas of the structure of the planetary system should undergo a great change. It is not strange that planets beyond the furthest known, should, as time advances, be discovered; but it does appear strange that planets and satellites should be discovered intervening between those formerly known; and we may well doubt whether there are not planets whose orbits lie between those of Venus and the Earth, and whether that body which we call the moon is the only satellite of the Earth. The importance of these discoveries is not to be judged of merely as a matter of detail, in which new particulars are simply added to old ones of the same class. Our conceptions of the structure of our system in particular, and of the sidereal system generally, may ere long be totally altered by the discovery of the almost universal prevalence of planetary and cometary bodies through all the space which our instruments command." M. de Gasparis, on the 11th May, 1850, discovered another planet belonging to the same group, which has received the name of "Parthenope," a graceful allusion to the place of its discovery. The period of revolution is found to be 1401 days, placing Parthenope between Hebe and Astræa in the order of mean distance from the sun. Its symbol is a fish crowned with a star. On the evening of the 13th September, Mr. Hind, at Mr. Bishop's Observatory in the Regent's Park, discovered a small planet, being the third member of the ultra-zodiacal group which has been detected by the system of examination of the heavens and formation of charts pursued there. It has received the name of Victoria, with a star and laurel-branch for its symbol. The period of revolution is 1303 days; its place in the order of mean distance will therefore follow Flora. M. de Gasparis, of Naples, found his third planet on the evening of November 2. Its place is between Parthenope and Astræa, and its periodic time 1496 days. It has received the name of Egeria. In acknowledgment of these discoveries, the Royal Astronomical Society have awarded M. de Gasparis its gold medal. With these additions the group of planets or asteroids, so frequently referred to, now consists of thirteen. While such unexampled success has attended the search for these primary bodies, observation has been no less successful in detecting the existence of attendant secondaries. The existence of one at least of the four satellites of Uranus, which, since their announcement by Sir W. Herschel, had been seen by no other observer, has been established by the observations of M. Lassell; it is the innermost of the series. M. Lassell has also obtained presumptive evidence of the reality of another, intermediate between the most conspicuous of those known. M. Otto Struve also has detected a secondary of the same planet; it is, however, not impossible that it may be the same as the first of those observed by M. Lassell; but if so, it is attended with the singular circumstance that the latter always saw the close satellite on the northern side of the planet only; M. Struve always on the southern. On the 19th September, 1848, M. Lassell distinctly observed another, that is, an eighth satellite of Saturn, to which he gave the name of Hyperion. It is a singular circumstance that this minute secondary was observed simultaneously by Professor Bond at the Cambridge Observatory, U. S. The reality of the satellite of Neptune, first noticed by M. Lassell in October, 1846, has been satisfactorily established, and its time of revolution round its primary calculated to be 5d 21h 12.4m. M. Lassell has been further enabled to announce his strong conviction, that he has detected a second attendant on that luminary. Having on the night of the 13th August observed the first satellite towards the southern elongation of the planet, on the following night he saw what he conceives to be another satellite in the line of the northern elongation of the old one, and about two diameters of the planet distant. Some other valuable observations on Neptune have been made; but the existence of its suspected ring has not been confirmed. A considerable number of COMETS have rewarded the diligence of observers. Dr. Petersen, assistant-astronomer to Professor Schumacher, at Altona, claims the honours of no less than three of these visitors. The first he detected on the night of the 7th August, 1849, in Auriga; the second on the evening of the 26th October of the same year in Draco; the third on the 1st May, 1850. Another comet was discovered almost simultaneously by three astronomers in three very distant parts of the globe. By M. Schweitzer on the 11th April, 1850, at Moscow; by Professor Bond at Cambridge, U. S., on the same day a few hours later; and by Mr. Graham, at Markree, on the 14th of the same month. M. Goujon, of the observatory at Paris, detected a comet on the night of the 15th April. Another comet was observed by Mr. Bond, jun., at Cambridge, U. S., on the 29th August. It was also seen by European observers a few days later. The reappearance of Encke's periodical comet was detected on the 27th August, 1848, by Professor Bond, of Cambridge, U. S. It presented much the same appearance as in 1828 and 1838; its general outline being elliptical, with a very sensible condensation of light on the side next the sun. The periodical comet of Faye has also reappeared in gratifying accordance with the prediction. Its ephemeris had been calculated by Lieut. Stratford, and his calculations had been examined by VOL. XCII. M. Le Verrier, who added the perturbations due to planetary attraction-a correction to the mean motion necessary to bring about a perfect accordance between theory and observation. The observations of Professor Challis, who detected it, confirm the accuracy of these calculations, and afford a gratifying proof of the progress which has been made in the theory and practice of this department of astronomy. As The disappearance of Saturn's ring (by its presenting its thin edge to the Earth), during the year 1848, was attended with some singular phenomena. Breaks or inequalities, such as would arise from irregularities in its structure were the matter of which it is composed unequally distributed in its different parts, were observed, when the edge only of the ring was visible. Hitherto these appearances have been noticed only on the illuminated side, but now on the unilluminated side also. these irregularities always retain one fixed position in reference to the globe of Saturn, the inference is, that the breaks in the illumination of the edge do not rotate about the ball. The first disappearance of the ring took place about the 30th June, and it reappeared between Aug. 31, and Sept. 3. It disappeared a second time between Sept. 12 and Sept. 13, and reappeared between Jan. 18 and Jan. 19, 1849. Much difference of opinion exists as to the form of this planet. Sir W. Herschel was of opinion that it was not elliptical, but like a parallelogram with the corners rounded off, and that the northern and southern regions were of a different shape: in the latter opinion his son Sir J. Herschel coincided. A series of mi2 F crometrical observations made by Mr. Main during the disappearance of the ring, shows that the form of Saturn without his ring is a perfect ellipse of considerable ellipticity. M. Lassell and Mr. Dawes have further made such observations upon the ring, that they became perfectly satisfied of its division into two distinct annuli, having obtained a perfectly clear and satisfactory view of the division. But a new and inexplicable phenomenon was added to the other marvels of this planet at the end of the year 1850. It was announced that Mr. Bond of Cambridge, U. S., had, on the night of the 15th November, discovered a third ring interior to the two others, and therefore at no great distance from the body of the planet. On the 3rd December, the Rev. Mr. Dawes and M. Lassell, examining Saturn at the private observatory of the former at Wateringbury, perceived phenomena analogous to those noticed by Mr. Bond; it appeared as though something like a crape veil covered a part of the sky within the inner (i. e. the second) ring, separated by a darker ill-defined boundary line from the solid body of the ring. Whether this be an innermost ring, or what other explanation may be assigned to it, these appearances are especially remarkable, because, in 1791 and the following years, Sir W. Herschel paid particular attention to the phenomena of this planet, and his observations amount to a negation of these of 1850 being then presented. It has been conjectured that they may be due to the total absence of sunshine from the southern side of the ring for the last fifteen years; a condition from which it has just emerged. A transit of Mercury over the Sun's disc, Nov. 8-9, 1848, was very carefully observed at most of the observatories, and afforded some curious phenomena. The passage of Jupiter's fourth satellite over the disc of its primary, in like manner, called general attention, and the somewhat singular phenomena which were exhibited were carefully noted. A total eclipse of the Moon on the night of the 19th March, 1849, was accompanied by circumstances which do not appear to have been heretofore remarked certainly not to the same degree. At Bruges, during the whole period of the adumbration, the shaded surface presented a degree of light quite unusual; it was of a deep red or copper colour, and even during the period of total eclipse the light and dark places on the face of the moon could be almost as well made out as in an ordinary dull moonlight night. The British Consul at Ghent, who was not aware that an eclipse was expected, wrote for an explanation of the blood-red colour of the moon at 9 o'clock. In England this appearance was less marked. Professor Challis, at Cambridge, describes it as "a faint ruddy light spread over the eclipsed portion of the moon's disc." Mr. Hind, at the South Villa observatory, says, "nothing unusual was remarked; the shadow had a greenish tinge." At Killaloe the colour "was much like that of tarnished yellow." Mr. Walkley, who observed the eclipse at Collumpton, says, "that the appearances were as usual until twenty minutes to 9 o'clock; at that period, and for the space of the next hour, instead of an eclipse, the whole phase of that body became very quickly and most beau tifully illuminated, and assumed the appearance of the glowing heat of fire from the furnace, rather tinged with a deep red. The whole disc of the moon was as perfect with light as if there had been no eclipse whatever." During the period of the eclipse there was a bright aurora in the north, and at Bruges a most magnificent meteor descended obliquely towards the horizon about the time of the central eclipse. Some very valuable treatises on Astronomical Science have been published within the last three years. Those which appear periodically and officially, it is not here necessary to notice; they all contain valuable contributions to the stores of the science. The reductions of the Greenwich lunar observations from 1750 to 1830 have been completed and published, a work, which, for magnitude, as directed to a special object, and for accuracy, has scarcely ever been equalled. The sixteenth volume of Cambridge Observations, containing the meridian observations of 1844 and 1845, and a volume of the Edinburgh Astronomical Observations, that for 1843, have been published. The observations of the late Mr. Fallows, made at the Cape of Good Hope in the years 1829, 1830, and 1831, have been printed at the expense of the Government. They were placed in the hands of the Astronomer Royal for reduction and exhibition in proper form; the work thus ably edited is regarded as the foundation of astronomy in the southern hemisphere. Some additions of great importance in the instruments and mechanical appliances of the science are worthy of note. At the Royal Observatory at Greenwich, a transit circle, with a telescope of eight inches aperture, has been substituted for the transit instrument and mural circle. For this operation no ordinary science, care, and mechanical ingenuity were required. An altitude and azimuth instrument, of remarkably massive and firm construction, has also been mounted at the Royal Observatory for the express purpose of observing the moon on every day on which it is at any time visible. At the Radcliffe Observatory, Oxford, an heliometer, by Repsold, has been erected in a building constructed purposely to receive it. The diameter of the dividing objectglass is 7 inches, with a focal length of 10 feet 4 inches. The hour-circle and declination-circle are each 2 feet in diameter. A new observatory has been founded and built at Liverpool. This building is constructed and furnished with instruments chiefly by the liberality of the Town. Council; besides a convenient house for the Astronomer, it contains a transit-room, an equatorial-room with a revolving dome, a chronometer-room, and a computing-room. The transit instrument has a telescope of 5 feet focus and 4 inches aperture; a transit clock and a mean-time clock by Molineux. The equatorial is a very fine instrument; the object-glass by Merz, of Munich, is 8 French inches in aperture, and about 12 feet in focal length. The clock-work is of most ingenious construction, having water for its motive power. Mr. Hartnup is appointed the first Director. The most gigantic instrument of the present day, and that by which the period will perhaps be most distinguished to future ages |