varying as the square of the distance inversely, was consequently for Mars 11.9 that for Jupiter. In order that the surface brightness should be the same for the two planets the reflecting power, or albedo, of Jupiter must for the part of the spectrum under consideration be 11.9 that of Mars. The visual albedo of Jupiter Professor Müller has found to be 2.8 that of Mars, as against Dr. Hartmann's ratio of 11.9 for the violet albedo, while Professor Lohse has found Jupiter's photographic albedo, where the ultra-violet is effective in addition to the violet, to be 18 8 that of Mars. Evidently the violet of Mars is relatively weak, and the ultra-violet very weak; as might be expected from the planet's pronounced reddish color. In the Astrophysical Journal for November Mr. Harrer of the Allegheny Observatory gives the results of his examination of the spectrum of a Orionis during the star's irregular minimum at the past opposition. Comparing his spectrograms of this period with Professor Keeler's spectrograms of 1894 he has detected no change in the number or relative intensities of the lines in the green and yellow of the spectrum. The American Academy of Arts and Sciences have appropriated the sum of $500 to assist in the construction of a large spectroscope to be used at the Yerkes Observatory by Professor Frost for the determination of motion of stars in the line of sight. In the choice of officers of the British Astronomical Association Mr. J. Evershed was reëlected for the current year director of the section of spectroscopy. A summary is given in Science of Dec. 8 of the results of Dr. Chase's careful investigation of the refraction of red stars. While the excess of red light in these stars might be expected by its smaller refrangibility to diminish the amount of their general refraction, Dr. Chase agrees with previous observers in finding that the refraction for the red stars is the same as for the other stars. In the Astrophysical Journal for November Professor Campbell reports that he finds variable motion in the line of sight for ẞ Capricorni and v Sagittarii. In the forthcoming 'Revised Harvard Photometry' a column is promised giving, for each star whose magnitude has been determined, the character of its spectrum; and also, where possible, the photographic magnitude will be given, by comparing which with the visual magnitude the star's color may be determined. Dr. Wilsing, continuing his investigation of the effect of pressure on spectra, has obtained (Astrophysical Journal, November,) by moistening carbon electrodes with water, results for hydrogen analogous to his previous results for other ele ments. Professor Hale has recently confirmed and extended his observations of carbon in the Sun's chromosphere (Yerkes Observatory Bulletin No. 12; Astrophysical Journal, November,). The green fluting of carbon, terminating at A 5165 was found in the chromosphere as long ago as September, 1897, the identification of the feeble bright lines of the fluting in the chromosphere being accomplished by first putting the slit of the spectroscope on the Sun's disc and then moving quickly to the Sun's edge, when the dark carbon lines were replaced by bright lines. In Aug. 1899 with the reconstructed spectroscope this green fluting was observed better than before, a large number of bright lines being visible. With perfect conditions and adjustments the yellow fluting, terminating at A 5635, was seen. The blue fluting, which terminates at λ 4737, could not be seen. VARIABLE STARS. J. A. PARKHURST. Minima of the Variable Stars of the Algol Type. The above ephemeris was computed from the elements given in Chandler's Third Catalogue with three exceptions. For U Cephei, Chandler's revised elements given in No. 396 of the Astronomical Journal; for DM. + 12°3557, Luizet's elements given in No. 3596 of the Astronomische Nachrichten; for DM. + 45°3062, Pickering's elements given in Harvard College Observatory Circular, No. 44. The long period variables must still await the appearance of an ephemeris in the Vierteljahrsschrit or the Companion to the Observatory. ANDERSON'S NEW VARIABLE IN HERCULES.-This is the first of the new variables noted on page 537 of the December number. The place there given is R. A. 17h 53m 27.7 55 24.7 Decl. 19° 29′ 41′′, (1855) The place was also measured by Dr. Hartwig with the 7-inch heliometer of the Remies Observatory in Bamberg, Germany. He gives as his results in No. 3603 of the Nachrichten The accompanying charts will aid in finding the field, which is 1° south of the 4.5 magnitude star 95 Herculis. The first chart, on the scale of the DM, gives the stars from the 6th to the 9 5 magnitude within a degree of the variable. The star a is DM. + 19°3439, b is 19°3494, and n is 19°3484. The larger scale chart gives enough of the stars from the 6th to the 12th magnitude within 10' of the variable to identify it in its fainter stages. COMPARISON STARS FOR ANDERSON'S NEW VARIABLe in Hercules. The magnitudes of the comparison stars are merely approximate, for the purpose of identification. The variation of this star has been somewhat rapid, as the following list of observed magnitudes will show, 21, not seen, 5 obs. Dr. Hartwig, in the place above cited, reports a decline of 0.25 magnitude between Oct. 3 and 14. When these observations are platted it will be seen that there is no check in the rapidity of the decline, and therefore no signs of an approaching minimum. The curve resembles that of Anderson's former discovery in this constellation, 6100 RV Herculis (See POPULAR ASTRONOMY, V, 326), which was followed below the 15th magnitude with the 40-inch Yerkes telescope. (Astronomical Journal, No. 456). If this resemblance is confirmed the star may reappear after minimum in the spring of 1900, in position for morning observation. THE SPECTRUM OF α ORIONIS DURING THE RECENT MINIMUM.— Mr. Henry Harrer, of the Allegheny Observatory, took six spectrograms of a Orionis during the interval 1898 December 24 and 1899 April 5, to seek for any spectral changes which might accompany the recent minimum. These plates were compared with three taken by Professor Keeler with the same instrument and the same adjustment in October and December 1894. The results of this comparison are thus stated by Mr. Harrer in a note in the Astrophysical Journal for November 1899. "The comparisons revealed no changes either in the number or relative intensities of the lines. The above six photographs therefore revealed no change in the spectrum of a Orionis within the limits which have been stated." About 130 lines were compared, between λ 5130 and 5655. ANOMALOUS MAXIMUM OF SS CYGNI.-If any apology were needed for the frequent reference to this variable, it would be furnished by Professor Bailey's discovery of so many examples of this type of variation in the cluster Messier 5, already noted in these columns. But these cluster variables are beyond the reach of an ordinary telescope, while all the changes of SS Cygni can be followed with a moderate aperture, so we must look to this star for most of our knowledge of this type of variation. The maximum just passed was unique in character. Nothing like it has been seen before, or at least been published, in the light changes of this star. If the form of curve for this maximum depended on the comparisons of a single observer, the report would perhaps be doubted, but the observations of the four are in so satisfactory agreement that the anomalous form of the curve seems well established. The accompanying graphic representation will show at once the form of the curve and the agreement of the observations (Compare curves in V, 271 and 387, VI, 159 and VII, 145). The star had reached normal light after the October maximum on Nov. 6, so that the period of quiescence was only 14 days, the shortest on record. The curve shows a maximum Dec. 1.7, the time of passing 9.35 magnitude during the rise being Nov. 28.1. Definite Orbit of Comet 1894 IV, (E. Swift).-In Astronomische Nachrichten No. 3606-7 Mr. F. H. Seares gives detailed results of a definitive calculation of the orbit of E. Swift's comet, from all of the published observations. It will be remembered that a similarity was noted, soon after its discovery, between the elements of the orbit of this comet and those of the long lost De Vico comet 1844 I. The previous calculations, although pointing strongly to the identity of the two comets, yet left much uncertainty as to the conclusion to be derived from them. To clear up this uncertainty as much as possible has been the object of Mr. Seares' investigation, and the new determination of the elements of the comet 1894 IV has been a first step in the investigation. The comet was so faint and the weather so bad that the total number of observations of the comet was only 64 for right ascension and 63 for declination. By comparing these observations with an ephemeris from Mr. Chandler's elements in Astronomical Journal No. 338 Mr. Seares formed seven normal places, and after correcting these for perturbations by Jupiter, Saturn, Mars, and Earth, calculated corrections to the elements by a least square solution of differential formulæ. The definitive elements thus obtained are as follows: Epoch 1594, Dec. 1.0. Osculation 1894, Dec. 10.0. π = 345 23 4".2 2 57 558 ± 11.1 土 44) i Ф = μ 34 1.4) 51 37.3 ± 7.1 605".9999 ± 0.0665. These elements place the perihelion passage on Oct. 12, 1894, and make the period 5.855 years. The next perihelion, neglecting perturbations, would be Aug. 20, 1900. GENERAL NOTES. It is scarcely necessary to say that the Leonids, though comparatively few in November anywhere, make something of a display in January from the pages of this magazine. Some of the charts present only a few true Leonids, and none a great many in view of what was expected, yet it has seemed best to give many reports from widely different localities in the hope that some useful data may be gained to help in solving some troublesome questions about the real location, dimensions and characteristics of the orbit of the Leonid stream of meteors. |