MAGNETIC OBSERVATIONS. 



193 



COEFFICIENTS OF THE DEVIATIONS OF THE FORWARD BINNACLE COMPASS. 



COEFFICIENTS OF THE DEVIATIONS OF THE FORWARD RITCHIE COMPASS. 



The values of the coefficients <) and ( for any compass should be constant. 

 Therefore the mean of all the observed values has been assumed as the truth, and is 

 given on the line marked " means" in the case of each compass. 



The constants thus far determined furnish the data with which to compute the 

 values of the coefficients %, 33, @, >, (, in any part of the world, for any of the 

 compasses under discussion. For convenience of reference these constants are 

 collected in the following table: 



The values of the coefficients 2(, 33, S, >, @, for each compass at each station, 

 were next computed from the quantities given in this table, in the following man- 

 ner. The coefficients 2t, >, and G are constant for each compass, and were taken 



25 December, 1872. 



