AND THE INTENSITY OF MAGNETICAL FORCE. 307 
observation, a result nearest to the mean of a complete series, and with it ascertained the 
dip at several localities noted on the map of Porter’s Island, beginning at the extreme 
western end as follows: 
Station No. 1, '77° 10’ -- 2 -==779 17’ 
eZ © 2,97 OF + Fosevrol4 
. rr uy 77 13 30” Complete Series at General Cunningham’s Office. 
“s © 4,77 13.54 7 = 77 20 30 
“6 677 20 + Yoke 77) 27 
“9% 6,77 85 +7 = 77 42 
“« «© 97,78 88 +7 = 78 45 
“ “ 8, 78 37 30 A full series, 
“© 9,98 25 + 7 = 78 32 
Mean, 77° 47’ 
Here, between the sixth and the seventh station, a distance of only four hundred and 
twenty feet, there is an increase of the dip to the extent of 1° 02’! 
78. a of Eagle River, Latitude 47° 27’, N.; oo sane 88° 23’, W.; os 18, 1843. 
Duration. , Be Calcul: te ad} HE: a Tots al intensity, 
Dip No. of | Epoch of commencing of 500. | 'Tempe-| duration Square of the Horizontal Total intensity, |that at Cincin- 
Needle. Vibrations. Sogo ge ager art at 60°, preceding. intensity. | Hor. being 1000. nati being 1000. 
| | 
77°54'30" 4 |10h.26m.59s.6 A} 138.0 | 81° |1878. |1898884.0000 |648.29 | | 
5 |12 838 569 6P/1681.2 | 88 5 1678.75 2818201.5625 647.80 | 
6 |12 02 O02 8 [1674.8 | 85 0/1670,85'2791739.7225 648.52 
| Mean, |648.20 3094.40 | 1036.72 
On the sandy beach at the mouth of a small river. As it was raining at the com- 
mencement of the: experiments, they were made within the tent, upon which the sun 
shone, as soon as the clouds and fog disappeared. Substratum, probably metamorphic 
conglomerate. 
79. La Pointe, Magdalene Island, W. 'T’., Latitude 46° 47’, N.; Longitude 90° 58’, W.; July 21, 1848. 
76°56'07"| 4 |10A.487.028. A\1324.2 | 80° 0)1320.28]1743139.2784|706.21 | 
5 |11 19 05 6 {1618.2 | 85 0/1610.12|2592486.4144/704.20 | 
6 |11 56 02 8 1608. 83 5)1604.4 |2574099.3600/703.74 
Mean,|704.72 8117.5 1044.50 
About half a mile eastwardly of the mission house, amongst the shady evergreens. 
Geology, lacustrine diluvium superimposed on sandstone.(?) Clear, wind south, unusually 
warm for the climate. 
80. Ontonagon River, Latitude 46° 52', N.; Longitude 89° 31’, W.; July 26, 1843. 
339,43|1794072.7249| 686.17] 3101.81 | 1039.23 
~77°13'10"| 4 | Gh.27m.593.6 A 1340. | 6 
On the east side of the mouth of the river. Alluvium, superimposed on sandstone. 
Clear, wind north-west. 
81. Rock Harbour, Isle Royale, Latitude 48° 06’, N.; Longitude 88° 47’, W.; ites & 28, — 
1380.17/1904869.2289 646.25 | 
yn 1225/646.56 
Mean, |646.40 3141.70 1052.60 
On the north side of the harbour, in a small opening amongst the fir trees, growing 
almost without soil, on a metamorphic sand rock, approaching, in its character, to trap 
“rook. 
6h.29m.048.4 P\1380.4 | 60° 
"78°07'36"| 4 
: 7 62 00 8 {1680.4 
voL. IX.—81 
