384 



SCIENCE. 



[N. S. Vol. II. No. 38. 



of stars some distance apart. The double-image 

 prism is placed at the focus and the two images 

 of the object glass are formed by two achromatic 

 prisms which can be slid to any desired distance 

 ft'om the focus. A Foucault prism and eyepiece 

 are placed behind the double-image prism. With 

 this instrument stars 35' apart may be brought 

 together. This form is recommended for large 

 telescopes for determining the brightness of the 

 fainter stars. 



On the Forms of the Disks of Jupiter's Satellites : 

 S. I. Bailey. Observations made at Arequipa 

 during the early part of the year indicate that 

 under the best conditions, II. , III. and IV. are 

 always seen round. I. was twice observed to 

 have an elongation, in each case being near the 

 planet. 



Note on the Magnesium Band at 1 5007 : H. 

 Cbew and O. H. Basquin. This fluting upon 

 being photographed plainly showed its bands .to 

 have a linear structure. A table gives the 

 wave-lengths of the main lines. > 



Note on the Spectrum of Carbon : H. Ceew and 

 O. H. Basquin. This confirms the work of 

 Kayser and Runge in showing by independent 

 e'S'idence that the three carbon bands at A 4216, 

 ^ 3883 and a 3590 were due to cyanogen. 



The Measurement of some Standard Wave-lengths 

 in the Infra-red Spectra of the Elements, II.: ExUM 

 Peecival Lewis. In this second paper on the 

 investigation of the infra-red spectra with the 

 radiomicrometer, measurements are given of 

 lines due to calcium, strontium and thallium. 



Preliminary Table of Solar Spectrum Wave- 

 lengths, VII.: Henry A. Rowland. The table 

 is continued from a 4903 to /I 5148. 



Resume of Solar Observations made in 189^ at 

 the Astrophysical Observatory of Catania : A. Mas- 

 CAEi. The months richest in the various phe- 

 nomena were May for spots and pores, July for 

 groups of spots and pores and for prominences, 

 and September for facute. The prominences and 

 faculse have been more numerous in the southern 

 than in the northern hemisphere. A marked max- 

 imum for the faculse occurs between 10° and20°. 

 There is a secondary maximum in the southern 

 hemisphere between 60° and 70°, and a decided 

 minimum in the polar regions. From the ta- 

 bles it is concluded that the secondary maxi- 

 ma of prominences of 1893 have moved toward 



the equator, while the absolute maximum has 

 moved nearly 10° south. The phenomena of 

 prominences and faculse have not been always 

 in complete accord. 



A Spectrographic Determination of velocities in 

 the System of Saturn : W. W. Campbell. The 

 work of the new Mills spectograph on the 

 Saturnian system has been a confirmation of 

 that of Professor Keeler. 



On the Existence of a Twilight Arc upon the 

 Planet Mars : Percival Lowell. Micrometric 

 measures of the equatorial diameter of Mars in 

 November showed an increase over those made 

 in October when the planet was nearer opposi- 

 tion, while the polar diameter remained practi- 

 cally unchanged. From this the author argues 

 the existence of a twlight arc of 10° upon 

 Mars. 



Spectroscopic Observations of Colored Stars: 

 Friedrich Krijegee. This is a list of observa- 

 tions of such colored stars as have not hitherto 

 been examined spectroscopically and of those 

 which required a review because of former 

 dubious results. 



Minor Contributions and Notes: Preliminary 

 Note on the Radiation of Incandescent Platinum. 

 The Visible Spectrum of the Trifid Nebula. Note 

 on the Spectrum of the Aurora Borealis. Observa- 

 tions of the B Band in Stellar Spectra. Note on 

 the Spectroscopic Proof of the Meteoric Constitution 

 of Saturn's Rings. Photograph of the Nebula near 

 43 Orionis Made at the Astrophysical Observatory 

 of Colonia. Note on the A Line in the Spectrum 

 of the Chromosphere. Etienne-Leopold Trouvelot. 

 The Belgian Astronomical Society. 



NEW BOOKS. 



The Alps from End to End. Sir William Mar- 

 tin Conway. Westminster, Archibald, Con- 

 stable & Co. New York, Macmillan & Co. 

 1895. Pp. xii-l-403. $7.00. 



Icebound on Kolguev. Altbyn TrevAR Battye. 

 Westminster, Archibald, Constable & Co. 

 New York, Macmillan & Co. 1895. Pp. 

 xxviii-l-458. $7.00. 



An Introduction to the Study of Zoology. B. 

 Lindsay. London, Levan, Sonnenschien & 

 Co. New York, Macmillan & Co. 1895. 

 Pp. xii + 356. $1.60. 



