54! 



Bowdltcli on correcting the apparent distance 



BC 



fourth 



8F^ Ji 



d 



econds. T 



lly called the 



the same as tlie fourth correction of 



WitchelFs method, which is generally neglected 



The last 



MS — MC is equal to \, SC% cot. d 



\W, cot. d, nearly. This is found in Table H, the argument at the 

 side being E, and at the top d. It is called the fifth correction, and 

 within the limits of the present table it is additive like the other 

 corrections^ though in fact, if it were of any sensible magnitude, it 

 would be subtractive when the distance is above 90% but for such 



distances and for altitudes exceeding 5° this correction is 



only 



a 



fraction of a second; and it is in all cases neglected by Witchell 

 and Lyons. 



