DETERMINATION OF ASTRONOMICAL REFRACTION. 83 



No times were recorded during the transits of the stars, 

 the whole attention being directed to bisecting the image 

 of the object under observation, with the horizontal wire; 

 the bisection was made at or near the intersection of the 

 centre wire of the transit system with the horizontal 

 thread. In a few cases this was impossible, but in no 

 instance was it found necessary to apply a correction for 

 curvature. 



The positions of the stars given in the appended list are 

 taken from Newcomb's " Catalogue of Fundamental Stars 

 for 1875 to 1900, Reduced to an Absolute System" the 

 numbers in the first column referring thereto. The positions 

 here given were reduced to the epoch 1905, adopting Pro- 

 fessor Newcomb's precessions and proper motions. The 

 coefficients to be combined with the data of the ephemerides 

 to obtain the reductions to apparent places were computed 

 with the formulae of the Nautical Almanac. The declina- 

 tions of the stars between - 77 degrees and the pole were 

 corrected for terms of the second order by the formula 



6 - S o = A5 o - [6-7367 - 10] Sin 8 o cos 8 Aa* 



in which o is the mean and S the apparent declination, 

 Aa o Ao o being the star corrections exclusive of the second 

 order terms. The number within the brackets is a logarithm. 



The heavy type indicates that the star transits below 

 the pole during the time of observation. 



