ains of Elam, found a cognate race already settled in Chaldea. Having with them built the great cities of Babylonia, they were themselves subsequently, between the 30th and 40th centuries B.C., conquered by the Semites, who are known to history as the Chaldeans. By this ancient people the divis ions of the zodiac, the days of the week, the months, and the year were established. Four and sixty were their most favorite subdivisions and multiples. Mr. T. J. Lowry, of the Coast Survey, describes a new instrument based upon the principle of the sextant, by which two adjacent angles can be at once measured by one observer. It therefore allows one person, by observing three distant stations, to fix his position in the three-point problem; the new instrument will doubtless prove of great service in surveying. Mr. Christie states that he has been employing for a year past the photometer invented by him, and finds that the prob able error of a stellar magnitude is only the twentieth part. A feeble red star is, according to him, more easily distinguished than a feeble blue star. It is proposed, on the occasion of the celebration of the centenary of the Genevan Society of Arts, founded in 1776, to distribute prizes to the makers of those chronometers which withstand the somewhat severe test applied by the committee of examination. The astronomical necrology embraces Mr. Henry Twitchell, who died on the 26th of February at Cincinnati, at the age of 59. Mr. Twitchell was for twenty years the honored assistant and the principal observer at the observatory of that city. Strictly speaking, he was the contriver of the first chronograph ever constructed. Hofrath Hennert Schwabe died, at the age of 85, at Dessau, Germany. His discovery, after forty years of observation, of the periodical nature of the phenomena of the solar spots, will long remain a brilliant example of the value of persevering observations. The Sun. The most important researches on the solar phenomena have been those of Professor Langley, of Pittsburgh. As the result of some six years' patient observations he has been able greatly to add to our knowledge of the peculiarities of the sun. After having succeeded in optical e first-fruits of the labors of the spectroscopic exam- ublished a discussion of numerous observations e Verrier has presented to the Paris Acade- ts obtained by Colonel Tennant by means blished the results of his discussion of the analyses of the structure of the solar surface, as was explained in the Annual for 1874, he has now called to his aid photometry and the thermo-electric pile. He finds that the nuclei of the solar spots are cooler than the neighboring bright portions of the sun's surface, but in general warmer than the limb of the sun as seen through the solar atmosphere. He has, moreover, shown that the light and heat which we receive from the sun emanates from the superficies of the nucleus, which is covered by a thin layer of gaseous material, which latter absorbs both heat and light; but in so doing exercises a distinct selective power in that the absorption of the lower or heat rays of the spectrum is to the absorption of the visual rays as one to six. He finds, moreover, that a sensible amount of heat is received from those portions of the lower envelope that are distant thirty seconds of are from the visible limb of the sun. Pickering and Strange have investigated, photometrically, the amount of light absorbed by the solar atmosphere. The probable error of the result is exceedingly small, and shows that the light at the edge is about four tenths of that at the centre. It appears to them that there is a slightly different distribution of the light across the polar and the equatorial diameters. Professor Mayer has continued to develop his method of obtaining the isothermals of the solar disk, and is now having a telescope arranged for the purpose of making continuous observations in this novel and interesting field. He suggests that the discordance in results obtained by Secchi and Langley may possibly be due to the fact that these observers have thrown the image of the sun upon inclined instead of horizontal disks of paper, thereby introducing superficial currents of air, whose presence he found extremely deleterious to his own results, and which were almost entirely obviated by employing a perfectly horizontal plane of projection. Although our review strictly begins with November, 1874, yet we will not omit to notice the work of Violle, published a little earlier than that date, on the effective temperature of the sun. Assuming that the mean emissive power of the sun is sensibly equal to that of steel in fusion, Violle concludes. that the true temperature of the sun is about two thousand degrees. As the first-fruits of the labors of the spectroscopic examination of the spectra of transparent substances, Lockyer announces the probable existence in the solar reversing layer of strontium, cadmium, lead, copper, cerium, and potassium. The eclipse of the sun of the 6th of April was successfully observed, the photographic observations in Siam being especially successful. It is considered that evidence of high importance was obtained bearing upon the general nature of the spectrum of the coronal atmosphere; the tendency being to conclude that the higher regions of the solar envelope differ chemically from the lower regions; the lower portions, in fact, being composed of less complex chemicals at a high temperature, while the lower temperature of the upper portions allows of the formation of more complex bodies. Fuhg has published a discussion of numerous observations of the diameter of the sun, and finds no difference between the polar and equatorial diameters. The views of Father Rosa as to the variable diameter of the sun have been already noticed by us. These views have been lately defended by Secchi, as the editor of the posthumous papers of Father Rosa. The Planets.-Le Verrier has presented to the Paris Academy of Sciences his numerical tables of the movements of Saturn. They are based principally upon the observations at Greenwich and Paris. This completes his work for all the bodies of the solar system, The measurements obtained by Colonel Tennant by means of Airy's double-image micrometer during the transit of Venus have been subjected by him to some discussion, and he thinks he has a decided indication of the elliptic form of the disk of the planet Venus. Dr. Galle has published the results of his discussion of the observations of the asteroid Flora, which were made in concert by various observatories for the determination of the solar parallax. His definitive result is 8.87", which agrees. very closely with the preliminary results derived by M. Puiseux from French observations of contact. From the concourse of various methods to its determination, we may be sure that this important element will soon be accurately known. No results for the value of the solar parallax, based on measurements of photographs, have yet been published. |