ON THE SQUARE BAK MICROMETER. 



175 



A (a' -a) 



-0.078 



A (8'- 8) -1.04 



CuKTATrRE CORBECTIOS, EqCATIOS (6). 



!. " 



iii'i-i'd - 32-6 : table Y. gives m' - 0.58 

 m^-tj) = 25.2 : table V. gives m = 0.34 



cos 8 sin 8 = 0.37 X 

 Correction = -0".09. 



<-m = 0.24 



Peopeb Motion CoBSECiioy, Eqdatioss (8) ajtd (9). 



Summary. 



a' -a. 



Uncorrected +2 23.38 



Refraction - 0.08 



Curvature — 



Motion - 0.54 



Corrected +2 22.76 



8'-8. 



Example IT. — .Bamard'.s comet, 1885 11., observed at Harvard College ob- 

 servatory ((;6 = 42° 22'.8), July 12, 1885. Square adjusted to apparent motion 

 as by case III. of article 10. Diagonal, 884".0. S^ = — 7' 42'.1. 



