290 OBSERVATIONS ON THE MAGNETIC DIP, 
* Urbana, Ohio, Latitude 40° 05’; Longitude, 83° 48’; March 3, 1838. 
s | Duration Calculated Total intensity, 
Dip. No.of | Epoch of commencing| of 500 |Tempe-| duration Square of the | Horizontal] Total intensity, |that at Cincin- 
mec Vibrations. pipredents rature. at 60° Preceding. intensity. | Mor. being 1000. |nati being 1000. 
‘ | 
a | 
a | 1 4h.84m.02s. P) 1577.663°5 |1577.00) 2486929.00 | 951.93 
, 2 5 18 02 0 1552.8 60 0 |1552.80| 2411187.84 | 954.53 
a March a1, 3 
10 21 04 GA) 1265.4:70 0 [1264.87] 1599896.12 | 953.32 
} Mean,| 953.26| 3027.9 1012.2 
Cliff limestone deeply covered with diluvial gravel. 
| Columbus, Ohio, Latitude 39° 57’, N.; Longitude 83° 02’, W.; April 2, 1838. 
4 71°04'52") 1 [11h.00m.055.6 AJ1559.6 | 49° |1561.60/2438594.56 | 966.69 
i 2 [11 41 00 8 {1538.8 | 50 |1541.00|2374681.00 | 964.95 
1 3 [12 39 04 4 {1254.0 | 51 |1254.65/1574146.6225] 968.28 
: Mean, 966.64| 2981.8 996.72 
Geology, cliff limestone. 
Il. SERTES, 1839, IOWA, WISCONSIN, &c. 
2. St. Louis, Latitude 38° 36’, N.; Longitude 90° 15’, W.; September 6, 1839. 
1h.02m.008. P| 1514.4/84°5 |1509.9512279949.0025|1038.40 
69°31'26"| 1 
2 11 42 00 1490.4/87 5 |1484,46|2203621.4916) 1048.18 
] 3 | 2 18 04 4 | 1211.9)87 0 |1210.00]1464100. 1042.32 
i | Mean, 1042.97*} 2981.50 | 997.35t 
Locality. Mrs. Asherly’s garden, near the reservoir, and the ancient mound-works. 
Geology. Horizontal carboniferous limestone. 
3. Davenport, Iowa, Latitude 41° 30’, N.; Longitude 90° 34’, W.; September 13, 1839. 
71° 55 | 1 | 3h.01m.018.2 P| 1591,6|70°5 1588.74(2524094.7876| 937.98 
2 |4 00 59 2 | 1568.8'69 5 |1566.64/2454360.8896| 941.91 
3 |4 49 02 8 | 1274.81.67  |1274.28/1623789.5184| 939.82 
| Mean,| 939.90} 3028.03 1012.91 
Declination 7° 50’, east, (surveyors.) Locality,—at the foot of the hill north of town; 
carboniferous limestone. 
4, Davenport again, on the hills north of Shoemaker’s Spring; Latitude 41° 30’; Longitude 90° 36’. 
71°55'15"| 1 | 8h.038m.085.2 Pi 1593.6 76° |1590.3 | 2529044.90 | 936.12 
2 3.43 04 4 | 1571.6) 75 |1568.2 | 2459251.24 | 939.32 
3 4 43 59 6 | 1276.4) '75 |1275.3 | 1626390.09 | 938.32 
| | | Mean,| 937.92} 3021.32 1011.00 
5. Lost Grove, (lowa,) Latitude 41° 39’, N.; Longitude 90° 25’, W.; September 23, 1839. 
72°02'26"| 3 | 2h.45m.038.6 | 1278. | 75° |1276.9 | 1630473.61| 935.96| 3028.46 | 1015.39 
Locality and geology. Near the point where the cliff limestone, coming up, with a 
gradual dip from the south, emerges from underneath the carboniferous limestone, to 
occupy the surface northwardly, nearly to Prairie du Chien. 
* Horizontal intensity at Cincinnati, August 18, 1840, being 1000, 
+ Total intensity at Cincinnati, August 18, 1840, being 1000, 
