ASTRONOMICAL OBSERVATORIES 



fractors to collect data for a statistical study of 

 double stars, stars which appear to the eye to be 

 single, but which are shown by the telescope to con- 

 sist in each case of two suns in mutual revolution 

 about their center of mass. This survey has not only 

 revealed over 4000 such systems, before unknown, 

 but has proved that at least one star in eighteen of 

 those as bright as the ninth magnitude is a double 

 star visible in the 36-inch refractor. Many thou- 

 sands of exceedingly accurate positions of the stars 

 have been secured with the meridian circle which 

 form important contributions to studies of the ap- 

 parent motions of the stars on the surface of the 

 celestial sphere. With the aid of the spectrographs 

 attached to the equatorial telescopes, extensive ad- 

 ditions have been made to our knowledge of the 

 spectra of nebulae, comets, new stars, and stars of 

 special interest. 



The observatory's most comprehensive investiga- 

 tion has been the measurement of the radial veloci- 

 ties the motions toward us or away from us in the 

 line of sight of the stars. With spectrographs at- 

 tached to the 36-inch refractor at Mount Hamilton 

 and to the D. O. Mills reflector at Santiago, the 

 radial velocities of about 1500 naked-eye stars, dis- 

 tributed over the entire sky, have been measured. 

 These data have been utilized in the solution of 

 many important problems concerning the stellar 

 system. Among the results thus obtained we may 

 note the following: The motion of the solar system 

 through space is about 12 miles per second toward 

 the boundary line between the constellations Her- 

 cules and Lyra; certainly one bright star in every 

 four, though appearing single in the most powerful 

 telescopes, is in reality a double star; the velocities 

 with which the stars travel through space are func- 

 tions of their effective ages, the speeds increasing 

 as the stars grow older. These observations have 

 shown, further, that the scale of the universe is 

 about 50 per cent larger than former estimates had 

 made it; that is, the brighter stars are, on the aver- 

 age, about 50 per cent more distant from us than 

 we had thought. 



Space limitations forbid reference to many other 

 important researches, and only permit us to men- 

 tion the extensive and unique series of photograpns 

 of the sun in total eclipse obtained by expeditions 

 sent out from the Lick Observatory at the expense 

 of generous friends. 



James Lick's gift of a great telescope and ob- 

 servatory aroused wide-spread interest and called 

 attention to the peculiar advantages for astrono- 



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