276 Rutherfurd Photographic Measures. 



VII. 



RESULTS OF THE MEASURES. 



The results of the several measures have been arranged in .tabu- 

 lar form at the end of the present section. The first column of the 

 tables gives the number of the plate ; the second contains the dis- 

 tance, expressed in divisions of the glass scale of the micrometer. 

 This quantity is given exactly as found in the observation books, 

 before the application of any corrections whatever. The following 

 column gives the distance, still in terms of the micrometer scale, 

 but corrected for runs and division errors, according to section II. 

 It is thus always possible to see the precise effect of the division 

 error corrections and runs upon the result of the observation. The 

 fourth column contains the final corrected distance in seconds of arc. 

 This quantity is obtained from the preceding column by using the 

 scale values given in Section Y., and applying corrections for refrac- 

 tion (Section III.) and aberration (Section IV.). Moreover, the 

 distances on the plate are really the tangents of the angular distances 

 of the stars in the sky, and it has therefore been necessary to apply 

 a further correction of* 



— ^ s 3 sin 2 i". 



This quantity has been taken, without interpolation, from the fol- 

 lowing table : 



* See Astronomical Journal, No. 233, p. 131. 



