eral catalogue so far as the double stars of W. Struve are concerned. It is a careful collection of all the measures of Struve in the "Mensuræ Micrometricæ," and in the minor works, and all these stars (above 3000 in number) are arranged in order of their right ascensions for 1875.0. For each pair all the particulars of magnitude, color, distance, position - angle, date of observation, even the magnifying powers employed, are given, as well as the co-ordinates, right ascension and declination for 1875. The precessions are to be taken from a table appended to the book. The full notes give further measures. Thus the particulars regarding each star are to be found collected on one line. If a reference to Struve's own measures is desired, a column gives the page of the original work where these may be found.

Flammarion, of Paris, has in the press a work on binary stars, etc., in which all observations are given for each star, and a discussion of their orbits, etc., follows.

Burnham, of Chicago, has lately discovered some interesting doubles, among which we may cite L 22020, p=60°±, s=0.5′′, mags. 9, 9; O. Arg. 11836, p=80°, s=1′′±, mags. 8,9; L 18231, p=70°, s=1.3′′, mags. 8.5, 10. These are remarkably difficult stars to be found with a six-inch aperture. Mr. Burnham also notes that 8 Sextantis A. C. 5 is a rapid binary, having moved 130° since 1860.

It may be definitely stated that the new companions to Polaris reported by Boë do not exist, as Mr. Burnham, of Chicago, has examined this neighborhood with the 18-inch refractor at Chicago without finding them.

Struve and Dubiago, of Pulkova, publish in the St. Petersburg Academy Bulletin a new investigation of the orbit of 1728 42 Coma Berenices. The orbit is based on thirtyeight measured distances alone (the apparent orbit being strictly a right line), and the observations are represented with unusual exactness. The period is 25.71±0.080 years. This orbit must be regarded as better established than that of any binary.

Gruber, of Buda-Pesth, gives the following elements for Eta Cassiopeia: Periastron passage, 1706.72; periodic time, 195.235 years; eccentricity, 0.6244; longitude of node, 33° 20′, of periastron, 229° 27'; inclination, 48° 18′ (1850.0). These

elements satisfy the normal places well: a=8.639", and Struve has found the parallax 0.154"; mass of the system, 4.63, that of the sun being 1, and a=56.10, the earth's mean distance being 1.

STAR CATALOGUES AND MAPS.

The progress made in the zones of the Astronomische Gesellschaft cannot be definitely stated until after the publication of the report of their meeting at Stockholm. The "Durchmusterung des Nördlichen Gestirnten Himmels," the joint work of Argelander and his assistants, Krüger and Schönfeld, embraces all the stars of the first nine magnitudes from the North Pole to 2° of south declination. This work was begun in 1852, and at its completion a catalogue of the approximate places of no less than 324,198 stars, with a series of excellent star-maps giving the aspect of the northern heavens for 1855, was at the service of astronomers, and has been in the most constant use from that time forward. Argelander's original plan was to carry this Durchmusterung as far as 23° south, so that every star visible in a small comet-seeker should be registered. His original plan was abandoned, but his former assistant and present successor at the Observatory of Bonn, Dr. Schönfeld, is now engaged in executing this important work. The same methods will be followed by Schönfeld which were so successful formerly; the equinox of 1855 is chosen as the fundamental one; and almost the only changes are the adoption of a telescope of six inches aperture for the work, and a closer discrimination of the magnitudes of the fainter order of stars. In the prosecution of the plan, Schönfeld has already determined the position of 74,885 stars; and astronomers in the northern hemisphere will soon possess an index, as it were, to every star likely to be used in their observations.

The last report of the National Observatory of the Argentine Republic is dated March, 1876. Dr. Gould reports that the Uranometry is ready for the press, except the text. The Zones, which were begun September 9, 1872, were finished August 9, 1875, and contain over 105,000 stars, and comprise the region from -22° 50' to 88° 10'. The Standard Catalogue now contains 4253 stars (12,661 observations), besides 54 circumpolars (1461 observations),

and the time stars (1684 observations). The observations. for the catalogue will terminate in 1877.

From a letter of Dr. Gould's we learn that the reductions of these zones are in a forward state. All observations are reduced to the middle of the field in both co-ordinates in duplicate. The reduction to 1875.0 is completed for 700 zones out of the 754; At, c, and n are computed for all the zones and two thirds of the refractions are completed. In February the work of printing the first meteorological volume commenced.

The maps of the Uranometry of the Southern Heavens, made by Gould and his assistants at Cordoba, are now preparing at Bien and Co.'s in New York. They are to be lithographed, and each map will be about half the size of the maps to the Durchmusterung.

From the annual report of the Astronomer Royal to the Board of Visitors we learn that the new nine-year catalogue is well under way, and that Sir George Airy will publish his numerical lunar theory as an appendix to the Greenwich volume.

The Paris Observatory continues the publication of ecliptic charts compiled from observations of MM. Henry.

Houzeau, of Brussels, has presented to the Belgian Academy a Uranometry of nearly 6000 naked-eye stars, which was constructed by him during a residence of thirteen months in the West Indies. It is presumed that this work will shortly be published.

The Cape of Good Hope Observatory has published a volume which contains the mean positions of 1246 stars, including all of Lacaille's stars in the "Cœlum Australe Stelliferum," which now fall between 155° and 165° N. P. D., and some additional ones in the same zone. Lacaille's stars between 145° and 155° N. P. D. were similarly observed in 1875, and those between 135° and 145° in 1876. We shall soon, therefore, have accurate places of all Lacaille's stars.

"Although the observations of the moon, planets, and comets made at Kremsmünster have been published from time to time, no publication of the results for stars has taken place, with the exception of a catalogue of 208 stars, printed in the Memoirs R. A. S., vol. xii. Reslhuber, however, reduced the observations of 560 stars to the epoch 1840; and

in order that this labor should not be altogether in vain, Herr Strasser, the present director, has incorporated with them his recent results for the period 1864-1874. He has thus formed a catalogue of 750 stars, all reduced to the epoch 1870, the two sets of observations being combined in case of agreement between the results."

Mr. Pogson, of Madras, has about 29,000 unpublished meridian observations of about 3000 southern stars, from which a catalogue is to be compiled and published. He is also making a complete atlas of telescopic variable stars in 136 maps, containing the approximate positions of over 40,000

stars.

Dr. Gyldén, director of the Observatory of Stockholm, has published the first part of Vol. I. of the annals of that observatory. It contains the observations of right ascensions. made at Stockholm during 1874, and a catalogue of the mean right ascensions of these stars for 1875.0. Part second will contain the north polar distances; part third will contain tables of elliptic functions of use in the calculation of the perturbations of comets.

Professor Safford, of Williams College, has prepared for the use of the United States Engineer Department Survey under Lieutenant Wheeler a catalogue of the declinations of 2018 stars, which is now passing through the press.

The catalogue of standard declinations, prepared by Professor Boss, of Albany, is now being printed.

Dr. Loewy, of Paris, has presented to the French Academy of Sciences a catalogue of 521 moon-culminating stars. The places of these depend upon observations made at the Observatory of the Bureau of Longitudes with portable instruments. The bureau has just completed the determination of the telegraphic longitudes of Neuchâtel, Geneva, and Lyons. It will shortly undertake the determination of the longitude of Lisbon. Knobel's important work on the Chronology of Star Catalogues is mentioned under Bibliography.

THE SUN.

In a paper published in the American Journal of Science and Arts, Dr. Henry Draper, of New York City, announces the discovery, by means of spectroscopic photography, of Oxygen in the solar atmosphere; and he brings the evidence

to the eye by printing from his original negatives the juxtaposed spectra of the sun and of the gas. In the photograph can be seen each bright line of the oxygen spectrum matched and prolonged by a corresponding bright line in the spectrum of the sun.

"While the metallic elements reveal themselves by dark lines in the solar spectrum, oxygen shows bright, and this is probably the reason why it has so long remained concealed; for these bright lines or bands which indicate its presence are inconspicuous and easily mistaken for mere unoccupied intervals between the multitudinous dark lines which abound in the portion of the spectrum where they are found. The attempt has always been to identify some of the dark lines of the solar spectrum with those of the element in question, and the bright bands escaped investigation until the photograph brought out their significance. Why oxygen should behave thus differently from the other substances before detected it is not yet possible to say with certainty. A possible explanation is that its very abundance has hidden it. A gaseous substance, sparingly present in the solar atmosphere, would declare itself by faint dark lines in the solar spectrum; but if the quantity of the gas should be gradually and continuously increased, these dark lines, after growing for a time more intense, would then by degrees fade away, and when the quantity of the gas had become sufficiently great, would be replaced by bright ones. But on this hypothesis it is very difficult to understand why oxygen is not conspicuous in the chromosphere; like the substance which gives the so-called D3 line, brilliant in the chromosphere spectrum, but invisible (usually) in the spectrum of the sun's surface. Probably the full explanation lies somewhat deeper."

Professor Langley, of Pittsburgh, publishes in the Monthly Notices, R. A. S., a paper on the measurement of the direct effect of sun-spots on terrestrial temperature. It is not intended to show that the earth is, on the whole, cooler in maximum sun-spot years, as the discussions on the paper (as reported in the Astronomical Register) indicate it to have been misinterpreted to mean. The observations consisted in measuring the relative amounts of umbral, penumbral, and photospheric radiation. The relative umbral, penumbral,