o72 SCIENTIFIC RECORD FOR 1885. 



tion becomes ditlicult. The case of Sirius is an interesting one, Irom 

 the fact that its motion has cbanged frooi a recession of 21 miles per 

 second in 1875-'76 to an approach of 21 miles per second in 1884. The 

 proof is very clear, the separate years giving: 



187G 21 miles per second ; recession 



1877 23 miles per second ; recession 



1879 15 miles per second ; recession 



1880 11 miles per second ; recession 



1881 2 miles per second ; recession 



1882 5 miles per second ; approach 



1883 .19 miles per second ; approach 



1884 21 miles i)er second ; approach 



"But the interest of this research is not in accumulating data as to the 

 motion of individual stars, however imi^ortant this may be. The real 

 point is, what light does this method throw upon the theory that the 

 sun, with the whole solar system, is moving toward the constellation 

 Hercules at a rate of some 590,000,000 miles per annum? Attempts 

 have been previously made to show that the spectroscopic data conlirm 

 the theory, which, indeed, has a fairly firm basis on other grounds. 

 Mr. Maunder declares that these attempts are premature, and that the 

 spectroscopic data are as yet insufficient. So far as they go, they rather 

 indicate a motion toward a Aquarii. 'Still, if the sun's speed be 

 small compared with the average speed of the stars observed, there is 

 nothing in the observations incompatible with the generally accepted 

 direction.' Mr. Maunder points out the fact that Greenwich Observa- 

 tory is the only observatory prosecuting these researches, which demand 

 a refined spectroscope, a large telescope, and a very clear and quiet 

 atmosphere — -conditions all lacking at the Royal Observatory. He ex- 

 presses the hope that the observatories of Nice and Melbourne may de- 

 vote their large telescopes to this work. In America we have several 

 large refractors admirably suited for the work, and it is to be hoped 

 that some of them may be exclusively devoted to it." {Ration, June 

 n, 1885.) 



PHOTOMETRY. 



Standards of stellar magmtudes. — The thiid report of the American 

 committee on standards of stellar magnitudes states that the zones fol- 

 lowing the twenty-four selected equatorial stars have received a second 

 careful revision with the Princeton 23-inch, which should make them 

 include all stars down to about 16-0 magnitude, and that a revision will 

 probably be made with the Washington 2G-inch. Four of the charts have 

 been distributed to all observatories having large telescopes, with re- 

 quests for all visible additions which will furnish comparisons of the pen- 

 etrating power of different kinds of telescopes. Certain selected stand- 

 ards in each zone, about 0-5 magnitude apart, have been measured at the 

 Harvard College Observatory with photometer I, and the two brightest, 

 if not too faint, with' the meridian-photometer. A catalogue of these 



