MAGNETIC OBSERVATIONS. 



191 



FORWARD RITCHIE COMPASS. 

 Equations of Condition. 



Normal Equations. 



+ 4983-3 



4- 16.291 

 4- 0.826 



4- 70.177 



4- 0.258 

 4-28.825 



/ = 



X 



G 



X 



AC? 

 X 



0.0141 



0.083 



O.OOI20 



+ 4983.3 



The value of the true A^ having thus become known for each compass, the 

 values of the coefficients 53, @, >, and (g, for each compass, at each station, wore 

 next computed by means of the formulae (16). The results, expressed in parts of 

 radius, are as follows: 



COEFFICIENTS OF THE DEVIATIONS OF THE ADMIRALTY STANDARD COMPASS. 



