of Bessel's Astronomical Observations. 



177 



The sum of the distances from the pole, measured by direct 

 vision and by reflexion, is the supplement of the double alti- 

 tude of the pole to 360° ; but it is to be corrected for flexure. 

 Hence I find 



a= + 1"-0646, probable error= + 0"-0563 

 b= +0*3175 ±0-0483 



The altitude of the pole free from the error of flexure is 

 = 54° 42' 50"'794, with the probable error +0"-0911. The 

 basis of this computation is the probable error of a direct ob- 

 servation =0"-7613, and that of an observation by reflexion 

 = l"-026 ; from which follows that of the double altitude of the 

 pole from a observations of the first, and a! of the second kind 



_ '. S (0"'7613)- (l''-026)> J 



~ V I a + a< S ' 



The following table contains the single results with and 

 without the correction, as also the probable errors. 



The mean agreement of the result is obtained by both me- 



thods; and the great number of observations from which they 



Vol. 64. No. 317. Sept. 1824. Z have 



