TEKKESTRIAL MAGNETISM. 



23 



Dip. 



Epoch of 

 commencing 

 vibration, 

 hrs. min. sec. 



Duration 





Calculated 



of 500 



1*1 



duration 



vibra- 



a s 



at 60°. 



tions. 



B >- 





Square of the 



Horizon- Total in- 

 tal inten- tensity : 

 sity. hor. be- 

 ing 1000. 



Total inten 



sity : that at 



Cincinnati 



= 1000. 



191. Bohemian Mountain.— Lat. 47° 25' N. Long. — ° — ' W. July 9, 1847. 



78° 30' 38" 



5 29 01 P 

 5 54 06 



1445.52 

 1440.34 



77 



1443.52 

 1438.19 



20837499904 

 20683904761 

 Mean 



875.63 

 871.59 

 873.61 



4281.9 



1464.6 



192. East and West Vein Mendelbaum's Mine, about half of a mile south of the 

 Bohemian Mountain. — July 10, 1847. 



89° 02' 00" Dipping-needle vibrated 30 in one minute. This extraordinary result was obtained 

 on a precipice looking southward, with a thin vein of blue sulphuret of copper 

 traversing from east to west. 

 From the above, and from the vibrations of the same needle at Cedar Swamp, on the 

 lake margin, we' deduce the total intensity (see below) 1182.4. 



193. Cedar S'wamp, at the landing of Sibley's Mine, margin of Lac La Belle. — June 10, 1847 



76° 52' 41" 



11 14 12 



1617.38 



82.5 



1614.76 



I 

 260744985761699.8 



3081.8 



1030.0 



194. Mount Houghton.— Lat. 47° 25' N. Long. 88° 04' W. July 10, 1847. 



77° 28' 00" 



5 31 01 P 



1636.39 



80 1634.10 



26702828100 683.40 3149.2 



1052.5 



195. Baits du Gris (Western Point).— Lat. 47° 22' N. Long. 88° 05' W. July 12, 1847. 



77° 25' 26" 



5 7 45 03 1640.39 75 1638.67 26852393689 679 48 3120.9 1043.1 



196. South Part of Point Kewenon.— Lat. 47° 26' N. Long. 87° 51' W. July 12, 1847 



78° 30' 39" 5 1 45 01 P 1689.6 87 1686.4 28439449600 641.57 3222.7 1077.1 



197. Point Ke"wenon, north-east angle, about two miles north of the preceding. — July 13, 1847 



78° ir 30" 5 5 24 05 A 1696.4 60 1696.4 287777296 634.03 3099.0 1035.7 



REMARKS. 

 191. Bohemian Mountain. — Range 29, township 58, section 29 ; United States surveys. Geology : 

 sienite. 



193. Cedar Swamp. — Range 29, township 58, section 32; south part. The same needle which 

 vibrated 30 in a minute at the above station, performed 28 vibrations in the same time. Of course, these 

 are but approximations. They indicate a high intensity at the east and west vein. Geology : sandstone 

 very near to the sienite, which rises very precipitously to the north. 



194. Mount Houghton. — Range 29, township 58, section 32; United States surveys. Geology: a 

 broad vein of red jasper. 



195. Baite du Gris ( Western Point). — Range 29, township 57, section 14. Geology : sandstone, 

 nearly horizontal. 



196. South part of Point Kewenon. — Range 27, township 58, section 27. Geology: sandstone, near 

 the junction of trap. 



197. Point Kewenon. — Geology: vesicular and amygdaloid trap, containing agates. 



