24 



OBSEKVATIONS ON 



Dip. 



ill 



Epoch of 

 commencing 

 vibration, 

 irs. min. sec. 



Duration 

 of 500 

 vibra- 

 tions. 



1 



Calculated 

 duration 

 at 60°. 



Square of the 

 preceding. 



lorizon- 

 al inten- 

 sity. 



Total in- 

 tensity : 

 tor. be- 

 ing 1000. 



Total inten- 

 sity : that at 

 Cincinnati 

 = 1000. 



198. Traverse, Presq'Isle.— Lat. 47° 11' N. Long. 88° 23' W. July 18, 1847. 



77° 08' 29" 



5 



5 25 02 A 



1631.4 



64 



1630.83 26596064889 686.04 3082.7 



1030.3 



199. Mouth of Portage River, or "Entrance."— Lat. 47° 01' N. Long. 88° 30' W. 

 July 18, 1847. 



77° 00' 30" 



5 



2 58 04 P 



1620.8 



71 



1619.2 26217086400 695.95 3098.7 



1035.6 



200. Anse.— Lat. 46° 49' N. Long. 88° 34' W. July 19, 1847. 



76° 51' 34" 



4 

 5 

 6 



4 31 03 P 



5 02 04 

 5 29 36 



1329.68 

 1613.52 

 1607.58 



76.0 



74.0 

 72.5 



1328.39 

 1611.94 

 1605.82 



17646199921 



25983505636 



25786578724 



Mean 



702.00 

 702.21 

 698.35 

 700.85 



3082.6 



1036.7 



201. Mouth of Huron River.— Lat. 46° 56' N. Long. 88° 09' W. July 21, 1847. 



77° 10' 48" 



5 



8 04 02 A 



1630.4 



73 



1629.0 



26536410000 687.58 3099.5 



'1036.9 



202. Mouth of Dead River.— Lat. 46° 34' 17" N. Long. 87° 33' W. July 23, 1847. 



77° 16' 36" 



4 

 5 

 6 



9 50 00.0 

 10 21 02.8 

 10 47 01.0 



1355.72 

 1644.40 

 1642.00 



80.0 

 79.5 

 80.0 



1353.96 

 1644.10 

 1641.10 



18332076816 



27030648100 



26932092100 



Mean 



670.27 

 671.31 

 669.39 

 670.32 



3043.1 



1017.1 



203. Jackson Mining Co.'s Office.— Lat. 46° 30' N. Long. 87° 43' W. July 26, 1847. 



77° 01' 26" 



5 



7 15 05.6 A 



1624 



61 



1624.3 



26283504900 



691.56 



3080.0 



1029.4 



204. Iron Mountain.— Lat. 46° 27' N. Long. 87° 49' W. July 26, 1847. 



77° 58' 10" 



5 



3 05 03 P 



1698.4 



60 



1698.4 



28835125600 



632.78 



3035.2 



1014.4 



KEMARKS. 



198. Traverse, Presq'Isle.— Range 31, township 55, section 16; United States surveys. Geology: 

 horizontally-stratified sandstone. 



199. Mouth of Portage River, or "Entrance." — Range 33, township 53, section 13. Geology: hori- 

 zontally-stratified sandstone. 



200. Anse. — Range 33, township 51, section 25; United States surveys. Geology: horizontally- 

 stratified sandstone. 



201. Mouth of Huron River.— Range 29, township 52, section 18 (?). Geology: sand, probably 

 superimposed on horizontally-stratified sandstone. 



202. Mouth of Dead River.— Range 25 N., 4th correction line, township 48, section 12. Geology : 

 sand, superimposed on sienite. 



203. Jackson Mining Co.'s Ofl&ce.— Range 26, township 48, section 28, south-west part. Geology: 

 metamorphic sandstone. 



204. Iron Mountain. — Range 27, township 47, section 1. Geology: anhydrous peroxide of iron. 



