RECTIFICATIONS AND ADDITIONS. 



455 



enriched the section on double stars. I had unduly omitted 

 to make use of the important labours of Monsieur Yvon 

 Villarceau, which had been read to the French Institut in 

 1849 (Connaissance des temps pour Tan 1852, p. 3 128). 

 I borrow here, from a table given by M. Faye of the elements 

 of the orbits of eight double stars, the (our first stars, which 

 he believes to be the most securely calculated. 



ELEMENTS OF THE ORBITS OF DOUBLE STARS. 



The problem of the period of revolution of rj Coronse has 

 two solutions : one being 42*5, and the other 66*3 years ; 

 but the latest observations of Otto Struve assign the pre- 

 ference to the second result. Mons. Ivon Villarceau finds 

 for the semi-major axis, excentricity, and period of revolution 

 expressed in years, of three other double stars, as follows I- 

 VOL. III. B B 



