June 24, 1904.] 



SCIENCE. 



965 



vestigations of the sun. The principal in- 

 strument to be ercted on the mountain is 

 the Snow horizontal telescope, recently con- 

 structed in the instrument and optical shops 

 of the Yerkes Observatory as the result of a 

 gift from Miss Helen Snow, of Chicago. This 

 telescope is a coelostat reflector, the coelostat 

 mirror having a diameter of 30 inches. A 

 second plane mirror, 24 inches in diameter, 

 reflects the beam north from the ccelostat to 

 either one of two concave mirrors, each of 24 

 inch aperture. One of these concave mirrors, of 

 about 60 feet focal length, is to be used in con- 

 junction with a solar spectrograph of 5 inches 

 aperture and 13 feet focal length; a spectro- 

 heliograph of 7 inches aperture, resembling 

 the Eumford spectroheliograph of the Yerkes 

 Observatory; and a stellar spectrogTaph pro- 

 vided with a large concave grating, and 

 mounted in a constant temperature laboratory. 

 It is hoped that it will be possible with this 

 stellar spectrograph to photograph the spectra 

 of a few of the brightest stars. For fainter 

 stars, the spectrograph is to be provided with 

 several prisms, for use singly or in combina- 

 tion. 



The second concave mirror of the coelostat 

 reflector is designed to give a large focal image 

 of the sun, especially adapted for investiga- 

 tions with a powerful spectroheliograph and 

 for spectroscopic studies of sun-spots and 

 other solar phenomena. The focal length of 

 this mirror is about 145 feet, so that it will 

 give a solar image about 16 inches in diameter. 

 The spectroheliograph for use with this large 

 solar image is to be of 7 inches aperture and 

 30 feet focal length. For the present, until 

 a suitable grating can be obtained, the dis- 

 persive train of this instrument will consist of 

 three prisms of 45° refracting angle, used in 

 conjunction with a plane mirror, so as to give 

 a total deviation of 180°. The motion of the 

 solar image, of which a zone about 4 inches 

 wide can be photographed with the spectro- 

 heliograph, will be produced by rotating the 

 concave mirror about a vertical axis by means 

 of a driving clock. A second driving clock, 

 so controlled as to be synchronous with the 

 first, will cause the photographic plate to move 

 behind the second slit. Three slits will be 



provided at this point, so as to permit photo- 

 graphs to be taken simultaneously through 

 as many different lines of the spectra. It is 

 hoped that this spectroheliograph will prove 

 to be well suited for use with some of the 

 narrower dark lines of the solar spectrum. 



The work of the expedition is under the im- 

 mediate direction of Professor George E. Hale, 

 director of the Yerkes Observatory. During 

 his absence Professor E. B. Frost will be in 

 immediate charge of the Yerkes Observatory, 

 with the title of acting director. Professor 

 Frost will also be the managing editor of the 

 Astrophysical Journal. Mr. Ferdinand Eller- 

 man and Mr. "Walter S. Adams will be asso- 

 ciated with Professor Hale in the work on Mt. 

 Wilson. 



Professor G. W. Ritchey, superintendent of 

 instrument construction at the Yerkes Observa- 

 tory, will be in charge of an instrument shop 

 which is being fitted up for the expedition of 



CARNEGIE INSTITUTION OF WASHINGTON. 



On May 18, 1904, the trustees of the Car- 

 negie Institution met, and after transacting 

 the necessary business to provide for the trans- 

 fer of all matters to the Carnegie Institution 

 of Washington, a charter for which passed 

 congress and was approved April 28, 1904, ad- 

 journed without day. The trustees named in 

 the act met at once and reorganized under the 

 new charter. The by-laws of the Carnegie 

 Institution were adopted as the by-laws of the 

 new organization, and the ofiicers of the old 

 organization were elected. General resolu- 

 tions adopting all the obligations, etc., of the 

 old institution were passed. Under the new 

 charter no questions can be raised as to the 

 competency of the institution to carry on the 

 operations outlined in the deed of gift of the 

 founder. 



The executive committee of the Carnegie 

 Institution of Washington met after the re- 

 organization and practically completed the 

 making of grants for the year 1904. It will 

 greatly facilitate the work of the executive 

 committee if all those thinking of making 

 applications for grants for 1905 will have 

 them in in September, as applications for 

 grants for 1905 will then be taken up. 



