456 



SCIENCE. 



[N. S. Vol. VIII. No. 197. 



review of work on ' The Spectra of Stars of 

 SeccM's Fourth Type.' The spectra of 22 

 stars of this type have been photographed 

 with the 40-inch Yerkes telescope, in most 

 cases with a dispersion of one prism. For 

 the stars Schjellerup 132 and 152, which 

 are the brightest specimens of this type, the 

 three-prism spectrograph was also em- 

 ployed. The photographs all show a large 

 number of lines hitherto unrecorded. Most 

 of these are dark, but there seem to be a 

 certain number of bright lines. These show 

 best with high dispersion, and are not 

 weakened in intensity by widening the 

 slit. The brighter ones have been observed 

 visually, in Schjellerup 132 and 152, using 

 a dispersion of three prisms. At Dr. 

 Hale's request the spectrum of Schjellerup 

 152 was observed visually with the 36-inch 

 telescope of the Lick Observatory by Pro- 

 fessors Keeler and Campbell, who concluded 

 that bright lines were almost certainly 

 present. Further tests of these lines are 

 being made at the Yerkes Observatory. 

 The wave-lengths of two of the brightest 

 of these lines agree very closely with the 

 wave-lengths of two of the brightest lines 

 in the spectra of the Wolf-Rayet stars, as 

 measured by Professor Campbell. It is 

 still too early to conclude, however, that 

 any connection exists between the stars of 

 the fourth type and those of the Wolf-Eayet 

 class. In this connection it should be re- 

 marked that the fourth-type stars, as plotted 

 by Mr. J. A. Parkhurst at the Yerkes Ob- 

 servatory, show a much stronger tendency 

 to cluster in and near the Milky Way than 

 any other stars except those of the Wolf- 

 Rayet type. It has been found possible to 

 arrange the spectra of eleven fourth-type 

 stars in a series, having at one end the star 

 DM 59° 2810 and at the other Schjellerup 

 155b. The investigation, which is being 

 made with the assistance of M. F. Ellerman 

 and Doctor Schlesinger, will be continued 

 during the coming year. 



Professor E. E. Barnard exhibited a series 

 of photographs illustrating the work that 

 had been done with the 6-inch aperture 

 lens. These consisted of photographs of 

 various portions of the Milky Way, show- 

 ing its cloud forms and intricate structure. 

 Many singular peculiarities were shown, 

 such as the great rifts where the Milky 

 Way appears to be rent asunder as if it 

 were breaking up. The impression is that 

 certain portions of the Milky Way consisted 

 of sheets of stars of comparatively little 

 depth, and it is in such regions that the 

 process of disintegration seems to be going 

 on. In some of the great clouds of stars 

 are shown very distinct black holes, in the 

 densest portions, as though tunnels perfor- 

 ated through the cloud masses and permit- 

 ted one to look into the blackness of space 

 beyond. Another striking feature is the 

 presence of vacant lanes or black channels 

 among the stars of the Milky Way. In 

 these no stars seem to exist. Still another 

 feature is the strange geometrical arrange- 

 ment of the stars in curves in certain re- 

 gions, as if some force were at work in this 

 structural arrangement, baffling for the 

 present direct explanation. One of the 

 most extraordinary features is the presence 

 of vast regions of faint diffused nebulosity, 

 mixing up with the stars of the Milky Way. 

 This nebulosity is better dealt with by the 

 photographic plate, because it is too faint 

 to affect the human eye. It is suggested 

 that when this remarkable feature comes 

 to be thoroughly studied, it will doubtless 

 lead to a better understanding of the phys- 

 ical condition of the Milky Way and of its 

 origin. 



The photographs of comets, especially of 

 Brooks' of 1893, show most remarkable and 

 rapid changes in the form and structure of 

 the tail. It seemed to suggest that the tail 

 may have encountered some resistance in 

 its flight through space. Comets are per- 

 haps the only objects that would be able to 



