PART II. LITERARY AND MISCELLANEOUS. CHAPTER I. VIEW OF IMPROVEMENTS IN SCIENCE DURING THE YEARS 1822-1823. ASTRONOMY: M. Nicollet's Observations on the Comet of 1822.-Changes observed by the Astronomer Royal in the Declination of some of the principal Fixed Stars.Optical Inventions of Professor Amici.-CHEMISTRY: Laws of Combination-Investigations of MM. Mitscherlich and Berzelius.--Newly Discovered Animal Acids.-PHYSICS: Finite Extent of the Atmosphere. Mathematical Laws of Electro-Magnetism, discovered by Professor Barlow. ----Baron de Humboldt on the Constitution and Mode of Action of Volcanoes.View of the Geodesical Operations performed in Italy from 1808 to 1814, and of the Trigonometrical Survey of France, now in progress. THE political events of the year 1822 possessing unusual interest and importance, and requiring a commensurate extension of space for their full developement, we found ourselves under the unpleasant necessity of delaying the chapter devoted to the improvements in science; so that it now becomes our duty to exhibit an outline of the progress of scientific research during that year, as well as the succeeding one, which forms the more immediate province of the present volume. In attempting, however, to execute this task, it is proper to premise, and the reader will have the goodness to keep it in mind, that all we under VOL. XVI. PART II. take is, merely to give a view of the more prominent improvements which have been effected during the period which this chapter comprises, and that anything like a general or detailed history is wholly incompatible with the plan of this work, and with the limits to which we are necessarily restricted. Our object is to furnish the general reader with a tolerably distinct and precise view of such discoveries and inventions in the natural sciences as are calculated to extend the boundaries of human knowledge, or to define and determine, with greater accuracy, those departments hitherto but imperfectly explored, and to fix a 2 A few of those great landmarks by which the philosophical historian is enabled to ascertain the amount of the progress of general science within a given period of time. ASTRONOMY. Comet of 1822.-The first object connected with the science of the heavens which solicits our attention is the comet which was discovered at Mar seilles on the 12th of May 1822, and observed at Paris, for the first time, on the 18th of the same month. From that day, the astronomers of the Royal Observatory were indefatigable in their observations, which were greatly facilitated by the tract of fine weather that followed its appearance, and from which M. Nicollet was enabled to calculate the elements of its orbit as follows:: Passage of the perihelion, May 6th, 1822, at 3h. 5. 11'. a. M. Perihelion distance, Inclination of the orbit, Longitude of the ascending node, These elements determine the orbit to be parabolic, though they bear no resemblance to those of the comet of 1204, which is still looked for, nor indeed to any of the comets which have been hitherto observed. This comet was very small, had little appearance of coma, and its recession from the earth was so rapid, that, from the 18th to the 31st of May, it described a distance equal to one half the distance of the sun from the earth. Changes in the Declinations of some of the Fixed Stars.-Mr Pond, the Astronomer Royal, has made some interesting observations on the changes which have taken place in the declination of some of the principal fixed stars. These anomalies, he was at first led to suppose, resulted from some alteration which had taken place in the figure of the instrument he employed, (the mural circle, which had recently been repaired by Troughton;) but he was soon convinced that there was no ground for this supposition, that the instrument was in every respect perfect, and that he might repose the greatest confidence in the precision and accuracy of the results obtained by it. This being the case, it is evident that if Bradley's catalogue of stars for the year 1756 were compared with the Greenwich catalogue for 1813, it would be possible to deduce the annual variation of each star for the mean period, or for the year 1784, supposing the proper motion of each star to have been uniform; and allowing for the precession of each star, a catalogue might be computed for any distant period, as, for example, the year 1822. Suppose such a catalogue, which Mr Pond has named the predicted catalogue, computed, then on comparing the predicted with the observed catalogue for the same year, considerable differences were found to subsist between them. The general tendency of all the stars was, to appear to the south of their predicted places, and this tendency seemed to be greater in southern than in northern stars; hence, if any star be found north of its predicted place, it will always be a star north of the zenith, and the quantity of its motion will be extremely small. Mr Pond also observed a much greater tendency to southern motion in some parts of the heavens than in opposite or distant parts as to right ascension; and in much the greater portion of the heavens, the southern motion seemed to prevail. Thus, a southern star, as Sirius, situated in that part of the heavens most favourable to southern motion, was found more to the south of its predicted place than Antares, situated on the part least favourable for southern motion, though it is itself more southward. Again, several stars were found to have moved more from their predicted places than other neighbouring stars, and, when this happened, the motion was invariably and without exception southward; no single star having any extra tendency to northern motion, which, indeed, in any star is so small, that it would never have excited attention. A very great deviation was observed in three bright stars, Capella, Procyon, and Sirius, the proper motion of each of which was southward, and therefore accelerated. The proper motion of Arcturus, though situated in that part of the heavens where the southern tendency is least discernible, is very great, and likewise southward. And, in general, the stars in the Greenwich catalogue, the proper motions of which are south, are nearly equal in number to those the proper motions of which are north; but the quantity of southern proper motion exceeds that of northern in the proportion of four to one. both of which hypotheses the facts are at variance. It would therefore appear, that these discordances arise from an astronomical cause, whatever that cause may be, and not from defects in the instruments, or errors in the observer; though it is proper to mention, at the same time, that Dr Brinkley, of Dublin, did not encounter similar discordances with the instrument he employed. In stars near the equator, the catalogue of Dr Brinkley differs five seconds from that of Mr Bessel; but from a consideration of all the probable causes of error, Mr Pond is of opinion, that the polar distances as given by Mr Bessel are too great by about three seconds, and the same distances as given by Dr Brinkley too small by about two seconds; and since Mr Pond's catalogue differs from the two former, from the zenith to the equator, in nearly the same proportion, there can be no reason to doubt that their errors throughout are divided in nearly the same ratio. "I am persuaded," Mr Pond concludes, "that the more this subject is considered, the more distinctly it will appear, that if any doubt can be entertained, founded on any circumstance arising out of the Dublin observations, that doubt must relate, not to the accuracy of former catalogues, but to the present position of the stars; since it is with respect to their present position that the two instruments are really at variance. This circumstance," he adds, is very fortunate, as time may confirm the present, or suggest some more satisfactory method of investigation, if what I have now advanced be not thought sufficient for the purpose." Mr Pond has very properly offered no conjecture as to the cause of these deviations, but devoted his attention" to the accumulation of numerous and accurate observations, from which alone any general law can be deduced. In the meantime, however, he has very satisfactorily shewn that the differences in question could not have arisen either from errors of the observer, or from defect in the instruments he employed, as, in that case, they would follow no law at all, or some law depending upon zenith distance, with Mr Ivory's Solution of the Problem of Double Altitudes. Various approximations have, at different times, been proposed for the solution of the problem of two altitudes; these, however, are seldom so eligible as the direct computation, which Mr Ivory has |