54 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 'JO 



1898 9a l?01) I 2 3 ^ J 6 / 7 \ 8 ^1910 



1898 £9 ]30U 1 ? 



't 5 G 7 S 9 10 



Figure i8. Continuation of figure 17. Curves for fields between 48° 

 and 66 west longitude, ^2° and 40° north latitude. 



