Sixty-tioo Stars about rj Cassiopeiae. 883 



In the next column are the special corrections* required by the 

 position angles of the Western impressions in consequence of 

 using the same zero point in measuring both Eastern and Western 

 impressions. "j" The sum of these two columns is then given in the 

 last column, which, therefore, contains the final correction as 

 actuall}' applied in the reductions. 



In Table lY. is given the tangent correction^ which is alwaj^s 

 negative and whose unit is .0001 divisions of the micrometer, 

 This table is a repetition of Table IV A. of Stars about ^5 Cygni, 

 but arranged in a form more suitable for use in connection with 

 Table Y, as will be evident later. It has been computed by the 

 formula : 



Correction = — ^ s^ (P sin^ i" = [i.ySSjn] s^ 



where s denotes the distance in divisions of the glass scale and 

 d is the value of one division of the scale in seconds of arc. 



Table Y. The first column contains the numbers of the stars in 

 order of right ascension and also in parentheses, for convenience 

 of reference to the original measures and plates, are the numbers 

 as assigned by Rutherfurd. The number of the plate is given in 

 column two after which follows the observed distances for the 

 Eastern impression. The numbers set down are the fractional 

 part of the measured distance expressed in divisions of the glass 

 scale, the whole number of divisions being ordinarily the same as 

 that given in the column corrected mean. In the case of one star 

 onh' (No. 58) the corrections have been sufficient to change the 

 whole number of divisions in passing from the observed distance 

 to the corrected mean. In columns four, five and six I have 

 placed the corrections as applied for refraction, § aberration |j and 

 scale^ respectively; these, with addition of the tangent correction 

 onl}- — which may be obtained directly from Table lY., being 

 practicall}' constant for each star — present all the corrections 

 which have been applied to the observed mean distance of the 

 East and West impressions to get the corrected mean of column 

 seven. It is therefore possible from this data to reproduce the 



*Ihid., p. 27^'. ?. Ibid., p. 253, et seq. 



tlMd., p. 240. II Ibid., p. 267. 



jlbid., p. 276. Tl Ibid., pp. 242-251. 



