AXD ADDITIONS. JLV 



The problem of the period of revolution of 17 Coronae admits of two 

 solutions : of 42'5 and 66'3 years ; but the late observations of Otto 

 Struve give the preference to the second. M. Yvon Villarceau finds the 

 semi-major axis, eccentricity, and period of revolution, in years : 



y Virginia 3"'446 0'8699 153787 

 Cancri 0"'934 0'3662 58-590 



dCentauri 12"-128 07187 78'486 



The occultation of one fixed star by another, as was presented by Her- 

 culis, I have called apparent (p. 287). M. Faye shows that it is a con- 

 sequence of the spurious diameter of the stars (Cosmos, vol. Hi. pp. 66 

 and 170,) seen in our telescopes. The parallax of 1830, Groomb ridge, 

 which I gave (p. 27) as 0"'226, is fouud by Schlttter and Wichmauo, 

 0'-182, and by Otto Struve, tt"'034. 



