102 RECORD OF SCIENCE FOR 1886. 



and in several cases where M. Wolf lias observed a faint companion to 

 a bright star, the photograph has shown that the magnitude of tlie 

 former was underestimated. One of the advantages of photogra[)hy 

 seems to be that it brings out faint objects which are lost to tlie eye, on 

 account of their proximity to bright stars. Besides the uebida discov- 

 ered about Maia, a nebulous streak has been seen near Electra, and 

 details of the Merope nebula have been made out, which had not been 

 recognized before, except by Common. 



Dr. Weiss has expressed a strong suspicion that all of the region to the 

 north and west of Alcyone is a vast nebula, only the brightest portions 

 of which are shown by our best telescopes. He recalls a statement by 

 Schmidt in 1803, that a small planet seemed to lose a part of its light 

 in traversing the region between Alcyone and Electra. 



Dr. Kammermann has been able to see the new Maia nebula with 

 the 10 inch refractor of the Geneva Observatory by masking the bright 

 star, and by using a special eye-piece provided with diaphragms, and 

 a plate of uranium glass, to increase the intensity of the chemical rays. 



A paper by Dr. Elkiu upon -'A comparison of the places of the Pleiades 

 asdetermined by the Konigsbergaud Yale College heliometers" was lead 

 at the Buffalo meetingof the American Association. Provisional results 

 show unquestioned changeof position with reference to //Tauri since 1840. 

 Most of the brighter stars of the group, as shown by Newcomb in his 

 " Standard Stars," go with ry Tauri, but among the smaller stars tliere 

 are de[)artures from this community of i)roper motion. Professor Pick- 

 ering has i)ointed out that the agreement of the si)ectra of certain of 

 these stars strongly confirms the probability of their physical connec" 

 tiou. 



ASTRONOMICAL CONSTANTS. 



Lcewy's method of determining the dements of rifraction. — M. Lcewy 

 has elaborated his method of determining the elements of refraction by 

 means of a reflecting prism placed in front of the object-glass of an 

 equatorial, and has submitted the problem to a careful mathematical 

 analysis in several i)apers communicated to the French Academy. The 

 full titles of these important papers are given in our " biobligrai)hy." Dr. 

 Gill speaks very highly of the plan, and has suggested some modifica- 

 tions of the details which he thinks would increase the ease and accu 

 ra(5y of observations. 



Oppolzer^s astronomical refraction. — The late Dr. von Ojipolzer i)nb- 

 lished in the Transactions of the Imperial Academy of Sciences, of 

 Vienna, a paper containing a theoretical discussion of the problem of 

 astronomical refraction followed by numerical tables intended to facil- 

 itate the ])ractical application of the results at which he arrived. When 

 the approximations are carried far enough, the. method seems capable 

 of giving results of great accuracy, even for large zenith distances. 

 A correction for gravity in the use (f rcfravtion tables. — Prof. Cleve- 



