M A (i N KTI C SI] K V !■: V OF PE N N BYLVANIi 



51 



interval of a month, the loss of magnetism of the Lloyd Needles is too small to 

 require any correction. 



I'ii/,/, of U< suiting Dips. 

 At those stations where the Lloyd needles were used, the dip was obtained bj 

 applying the correction e to the results by the needle when unloaded; when the 

 dip was also observed in the ordinary way, the result bj the Lloyd needle 

 allowed the weight one-half, as it depends on half the number of observations. 



1 By Lloyd 1. 



8 



By Lloyd 3. 



1 Bj 1 • qnal wi ight with LI. 1 .in I 1.1. :;. 



