38 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



what surprising when we consider the extent of the work 

 and the rapidity with which it is done. A portion of the 

 zones will cross the Milky Way, and it will be attempted to 

 give the position of every star visible in this region with the 

 help of telescopes often inches' aperture. Bullet. Ilebdoma- 

 daire, 1875, 335. 



ON THE RECTILINEAR RELATIVE MOTION OF THE COMPONENTS 



OF THE STAR 61 CYGNI. 



Mr. Wilson has examined the relative motion of the com- 

 ponents of the double star 61 Cygni, with the intention of 

 ascertaining: how far recent measures confirm Struve's con- 

 elusions that this motion is rectilinear. If these stars were 

 physically connected in a binary system, it would be highly 

 improbable that their apparent motions as seen from the 

 earth would be sensibly straight lines. And yet, during the 

 past century, the observations, which have been numerous, 

 show that their motions really are so. On the other hand, 

 the fact that they both have very large proper motions, 

 being respectively 517 and 509 seconds per century, and in 

 the same directions, leads to the conclusion that in all prob- 

 ability there must be some connection between them. Wo 

 have thus the remarkable phenomena of two stars close to- 

 gether, animated by an unusually great proper motion, yet 

 whose physical connection is still in doubt. Mr. Wilson's 

 studies upon this subject seem not to contribute any thing 

 toward a solution of our present doubts. He is merely able 

 to confirm the fact that all known observations may be suf- 

 ficiently well explained by the assumption that the two stars 

 are moving in straight lines. Notices of the lloyal Astro- 

 nomical Society, April, 1875, 324. 



THE TRIPLE STAR ZETA CANCRI. 



The triple star Zeta Cancri has for manv vears formed an 

 object of study on the part of Otto Struve, who has recently 

 published an excellent memoir on the relative movements of 

 its components. The first observations of this star were by 

 Tobias Mayer in 1756, who recognized it as double, and de- 

 termined the relative position of the components. Similar 

 observations were made in 177S by Christian Mayer. Sir 

 William llerschel, in 1781, made the interesting discovery 



