TEERESTRIAL MAGNETISM. 



29 



Baite du Gris 



a 



Hawk's Bill 

 Portage River 

 Anse 



western part 



Latitude. 



47° 24' 00" 



47 22 00 



47 11 00 



47 01 00 



46 49 00 



08' 00" 



05 00 



30 00 



30 00 



34 00 



Total intensity. 



1041.5 

 1048.1 

 1030.3 

 1035.6 

 1036.7 



47 09 06 88 21 06 1038.3 



Total intensity, reduced to arbitrary scale 1.8637 



The observations at La Pointe and at Ontonagon River were made on the same 

 sandstone. The results are as follows : — 



La Pointe 

 Ontonagon River 



Latitude. 



46° 47' 00" 

 46 52 00 



Longitude. 



90° 58' 00" 

 89 31 00 



Total intensity. 



1044.5 

 1039.0 



46 49 30 90 44 00 1041.7 



Reduced to arbitrary scale, total intensity ....... 1.870 



South Shore op Lake Superior, from Chocolate River to Taquajianon. 



Latitude. Longitude. Total intensity. 



Train River 46° 30' 00" 



. 46 27 00 



. 46 43 00 



. 46 43 00 



. 46 42 00 



. 46 43 00 



. 46 46 00 



. 46 41 00 



Grand Island . 

 Chapel River 

 Portal Rock 

 Grand Marais 

 Two-Heart River 

 Near White Pish Point 

 Little Taquamanon River 



Longitude. 



87° 01' 00" 

 86 45 

 86 40 



39 



09 



38 



13 



13 



86 



00 

 00 

 45 

 00 

 00 

 00 

 00 



1042.000 

 1045.000 

 1049.000 

 1049.000 

 1043.000 

 1041.000 

 1052.000 

 1046.000 



46 39 22 



By arbitrary scale . 

 Maximum of Col. Sabine 



86 09 50 



1045.875 



1.877 

 1.878 



These observations, which are remarkably consistent, and made along a sandstone 

 coast entirely unexceptionable as regards the geological formations, exhibit a mean 

 within a unit of being equal to the maximum of Col. Sabine. Why it should be 

 higher than a mean of the most unexceptionable observations on Kewenon peninsula, 

 it is difficult to decide, unless the cold water of the lake, extending along so nearly 

 a magnetic parallel, has some modifying influence. 



It appears that the intensities, as indicated by No. 5, are higher than the mean 

 where the three needles have been used. In order to be able to apply an equation 

 where No. 5 alone was used, I have made comparisons of nine cases in which two 

 or three needles were used. I find by the mean of this comparison that the ratio 

 of the indications of No. 5 to those of the means of the several needles, is as 1 to 

 0.99852. The mean of total intensity at eight stations along the south shore of 

 Lake Superior, from Train River to Little Taquamanon, by No. 5, is equal to 1046, 

 or by arbitrary scale 1877.6, which, being reduced by the above coefficient, is 

 1874.8 



