CATALOGUE OF POLAR STARS. 



247 



It will be found convenient to represent the entire coefficients of (/' — /„), if — t^f, 

 {f — Uf> {f — tofj &c., in equations (14) and (15) by a single expression. 



Let 



and 



&c., &c. 



Then writing ^ for it' — 4) we have, 



« = «„ + ri ^ + t'n <= + c^ ^ + r'^ <^ &c. 



d = 5„ + TF' C + IF" i!= + TF™ <' + TF"' ^S &c. 



(48) 

 (49) 



We now compute the right ascension of Groombridge 1119 for t = -IQ, -40, -SO, 

 -120, corresponding to the years 1855, 1835, 1795, and 1755. 

 With the data 



'^=+73!514324 ^ 

 dt dt^ 



and the values of 



= -.30237888 



d^n 



df 



= -.0020374621 



d*a 

 dt* 



+ .00008334240 



The corresponding values of a obtained from equations (G) are : 



h. m. s. 



7 3 88.153 

 giving the deviations 



+ o!bi2 



h. m. s. 



6 36 34.034 



+ 0.256 



h. m. s. 



5 40 10.397 



-2.577 



h. m. s. 



4 45 55.203 



-98.449 



