SOLUTION OF THE EQUATIONS. 



607 



(4) It also appears from the above Tables that those constants in 

 the values of which Gauss and Erman greatly differ are those which have 

 undergone the greatest changes in the interval from 1845 to 1880, and that 

 the values for 1845 now determined for the most part agree more nearly 

 with those of Erman than with those of Gauss*. 



12. The values of the magnetic constants have been determined from 

 the equations for (X) and ( Y) combined, and from the equations for (Z) 

 separately, as well as from the equations for (X), ( Y) and (Z) combined, 

 and their values have been compared. Also their values have been deter- 

 mined (1) by including all the equations up to (e), i.e. between latitudes 

 67-2- N. and G7-J S., as given in the following table, and (2) by including 

 all the equations up to (c), i.e. between latitudes 77|- N. and 77^- S. 



Comparative Values of the Magnetic Constants in British Units as deduced 



from different magnetic elements. 



J* It should be remembered that before the excellent Admiralty Charts of 1880, pre- 

 by Captain Creak, the magnetic charts of the world were based on observations 

 which were insufficient and not distributed widely or regularly over the Earth's surface.] 



