The Rev. Dr. Robinson on the Constant of Refraction. 



203 



J 9 X (^R = — 7".65 rfR = — 0".40 



K = 4.4839 dfi — - 0.090 



64 ^ Cygni. 



Twelve observations (1838. 767) give, 



8 = + 43° 15' 11".98. 



Precession = + 14". 104 ; sec var. = + 0".219 ; proper motion = + 0".033. 



14 X (^R = — 21".30. 

 K = 5.6710. 



dK = — I". 52. 



dn= — 0.268. 

 2d2 



