one hundred and eighty-two years; the inclination of the orbit being 47.5 degrees, and its eccentricity 0.5. The probable errors of the measurements of the distance of the stars is scarcely one tenth of a second. According to the ephemeris published at the conclusion of the work of Venogradski, the relative movement of these stars is at present at its maximum.—Journal of the Imperial University at Kasan, XLI.,

311.

SPECTRA OF THE FAINT STARS.

Vogel states that for some time past he has been almost exclusively occupied with the spectroscopic investigation of faint stars. Among these are some that are distinguished by having spectra which are sharply defined at the violet side, but on the red side are broken up into gradually diminishing bands. These are generally red stars. By a somewhat careful study of these spectra it seems to him undoubted that their discontinuity is only apparent, being brought about by dark bands of absorption, which, as we must assume, are the consequence of the absorption of the rays of light by the atmospheres surrounding these stars. The only rational classification of star spectra is, according to him, into the following three classes: 1. Stars whose temperature is such that the metallic vapors contained in their atmospheres can exert only a very slight absorptive effect. 2. Stars whose atmospheres, as in the case of our sun, are distinguished by powerful absorption due to vaporized metals. 3. Stars whose temperature is so lowered that the materials which compose their atmospheres can combine together. In the latter class. Vogel embraces both the third and fourth types of spectra established by Secchi.-Astronom. Nachrichten, LXXXIV.,

115.

ON THE SCINTILLATION OF THE STARS.

Montigny has lately presented to the Royal Academy of Brussels a continuation of his researches on the scintillation of the stars. In this work he has studied not only the number of bands in the spectra of the stars, but also their growth, and especially the obscurity of the lines and zones which characterize the bands. Making use of the obser vations of Secchi, he thinks he has been able to show with

considerable exactness the connection between the frequency of the scintillations and the characters of the spectra, having regard especially to the four types that have been proposed by Secchi. The comparison of his own and Secchi's observations leads him to the conclusion that the stars which have been chosen as showing spectra typical of the first and second classes are also those which have the most frequent scintillations. The typical stars of the fourth class of spectra are those whose scintillation is the most feeble. Those stars of the first class which scintillate less than the typical stars are in general distinguished by having less numerous spectral lines. These conclusions he subsequently finds confirmed by the observations of Huggins and Miller. His essay concludes by a calculation of the actual differences between the lengths of the routes through the air of the components of the light of any star, and this leads him to a formula which is applicable to the calculation of the relative frequency of the scintillations of various stars at different zenith distances.-Bull. Roy. Acad. of Belgium, 1874, 300.

THE STRUCTURE OF SOLAR SPOTS.

The study of the solar spots has very wisely been made a matter of especial attention at the observatory of Allegheny City, Pennsylvania, and Professor Langley, the director of that institution, has the credit of having published the finest photographs and engravings that have ever yet illustrated the subject. From the very cautious wording of a recent communication from him, we gather that among the typical characteristics of the solar phenomena he has observed the following new points: 1. The filaments both of the penumbra and of the umbra are all disposed in curves, which partake of the spiral type, bearing witness to the existence of a force directed toward the centre of the spot; but it does not appear that a uniform direction of rotation prevails, since some of the filaments turn to the one, and some to the other direction, while some have a distinct double curvature. 2. The filaments grow progressively brighter toward their extremities, no matter whether they are long enough to reach from the photosphere to the edge of the penumbra, or whether they are shorter than this. 3. He finds the blackest part of the spot to be intrinsically very bright, and its reddish-brown

masses are by his telescope resolved into filaments analogous to the penumbral ones, being disposed in curves, and having brighter extremities, as if their ends curled upward. Langley sees no evidence of crystalline forms, but judges rather that we seem to look down through increasing depths of transparent whirling vapor, visible objects growing fainter till lost to sight at an unknown depth below the surface. The striking forms seen in the solar atmosphere are, he thinks, most nearly typified by certain rare types of cirrus clouds in our own atmosphere. In very many spots Mr. Langley recognizes the movement of one stratum of solar atmosphere over another.-4 D, IX., 192.

AGREEMENT OF SECCHI'S VIEWS WITH PROFESSOR LANGLEY'S. The very beautiful solar drawings published in the American and Italian journals by Professor Langley, of Allegheny City, together with the announcement of the conclusions reached by him from his study of the solar spots, has called forth some remarks by Secchi, of Rome, in which the latter seems to claim a certain amount of priority in respect to the ideas of Langley, and to maintain that they agree with each other to a very considerable extent. This, however, can only be true in case Secchi relinquishes certain of his long-held theories, and it is, therefore, important to put on record his conversion to the views of Professor Langley.

WHITE LINES IN THE SOLAR SPECTRUM.

Mr. Hennessy writes, from Massorie, to Professor Stokes, that he has observed in the solar spectrum certain white lines for whose existence he is unable to account. He can not think that these are due either to the instrument or to the latitude of the station. The white lines in question can not be described as absolutely white, yet they closely resemble threads of white frosted silk held in the sunlight. They are best seen about noon.—7 A, XLVIII., 305.

PHOTOGRAPHS OF STELLAR SPECTRA.

Mr. Lockyer, in a recent lecture on spectrum photography, gives great prominence to the admirable labors of Messrs. Rutherford and Draper in New York City, stating that the latter gentleman has not only taken the most perfect photo

graph of the solar spectrum yet obtained, but has succeeded. in getting an admirable photograph of the spectrum of a star. It will thus become possible to study any changes that may take place in the constitution of the stars or the sun by the comparison of these photographs with such others as may be taken at some future time.-12 A, X., 255.

ZÖLLNER'S THEORY OF THE SOLAR SPOTS.

The theory of Zöllner as to the constitution of the sun and its spots has been thus described by him: The sun is a glowing liquid body, surrounded by a glowing atmosphere; in the latter, at a certain distance above the fluid surface, there floats a covering, constantly renewing itself, of shining clouds, like our own cumuli. At those places where the cloud canopy is thinned, or dissipated, there arise on the glowing surface, by reason of powerful radiation, the slag-like products of cooling. These, therefore, lie deeper than the general level of the shining clouds, and form the nuclei of the sun spots. Above these cooled regions there are formed descending currents of air, which give rise to a circulation of the atmosphere around the edges of the islands of slag, to which circulation the penumbra owes its origin. The cloud-like results of condensation, which are formed within the region of this circulation, have their shape and temperature determined by the nature of the circulation itself, and must, therefore, in consequence of their lower temperatures, appear less brilliant than the other portions. of the cloud canopy of the solar surface, and seem depressed like a funnel, by reason of their descending motion above the spot. The exterior edge of the penumbra is at the level of the shining canopy.-Poggendorff Annalen, CL., 300.

ANCIENT OBSERVATIONS OF SOLAR SPOTS.

In the 29th volume of the meteorological observations at Lyons, France, an account is given of some early observations of the solar spots made by Father Beraud. In 1741, on the 8th of April, he observed eight pretty large spots on the sun. From the 16th to the 30th a remarkable spot fixed his attention. It was composed of an obscure portion of irregular form, situated between two black points, the whole enveloped by a brown cloud composed of small black

points. The whole had a round form, whose apparent diameter was 55 minutes of arc, or three times the diameter that the earth would appear to have if placed at the same distance.-13 B, III., 134.

THE SOLAR ATMOSPHERE.

Zöllner has published in detail his defense of his views as to the nature of the solar spots, basing his reasoning principally upon laws announced by Kirchoff in his investigations of the solar spectrum. He first shows that if the lowest strata of the solar atmosphere radiate as intensely as they absorb, clouds in that atmosphere will be scarcely distinguishable, so far as any difference of brightness is concerned between them and the neighboring atmosphere; and, secondly, he states that it is not sufficient to assume the existence of clouds, but that some reasonable cause must be assigned for their continued existence for weeks and months. In his exhaustive analysis he shows that local cooling can not be explained by conduction of heat, and that, therefore, up-rushing or down-rushing currents of cooling gas can not be produced by this cause. The influence of radiation being thus the only resource left, he draws analogy between the solar spots and the formation of dew in the earth, and seeking those circumstances under which the radiation from the surface of a body is localized for the longest time, he finds that such radiation proceeds most freely when the body is a solid; hence he concludes the solar spots to be of a solid nature.-Poggendorff Annalen, CL., 298.

THE DIMENSIONS OF THE SUN.

Some of the results of the studies of Secchi having been severely criticised by Anwers, he has recently edited a work by Father Rosa, which will, in part, serve as an answer to these criticisms. The investigations of Rosa and Secchi are based upon observations made during the past hundred years at Greenwich, Dorpat, and Königsberg, and Secchi believes. that they show that the body of the sun must be considered as consisting of two quite independent masses, viz., a solid nucleus, surrounded by an atmosphere of gas. Instead of the solid nucleus, we may also understand the central portion. to be a mass of gas in such a state of condensation that it is