52 ON MAGNETISM. 



a system is represented by the diverging strong lines in 



Figures 20 and 21, which are maps on the stereographic 



Fig. 21. 



(A is the South Magnetic Pole. See Article 42.) 



projection. (Although this system is essentially found- 

 ed on observations, collected about forty years ago, 

 some portions of it in inaccessible regions of the Earth 

 are supplied from a theory of Gauss's, to which we shall 

 soon allude: some small alterations would be required 

 to make it quite correct for the present date.) The 

 forms of these Magnetic Meridians are very remarkable. 

 None of them appears to be exactly a great circle. 



