AND THE INTENSITY OF MAGNETICAL FORCE. 299 
42. Philadelphia, March 31, 1841, 
. Duration Caloulated ’ | a ge ‘Total intensity , 
Dip. No. of | Epoch of commencing} of 500 |'Tempe-| duration Square of the Horizontal |'Total intensity, that at Cincin- 
Needle. Vibrations, Vibrations.| rature. at 60°. preceding. intensity.| Hor. being sat 2 tome being 1000. 
72°01'20"| 1 |12/4.382m.00s.8 {1605.6 | 51° |1607.34)2583541.8756 917.11 
2 1 22 04 4 {1585.2 | 50 5/1587.38/2519775.1644 916.53 
3 Tl -O7-. 00 1290.5 | 51 {1291.17)1667119.9689 916.12 
4 2 b2° 02 8 -jIros, 51 5]1158.'75/1842001.5625 918.53 
5 3 22 59 6 j1410. 50 |1410.84)1990469.5056/916.53 
6 3 55 02 8 {1404.8 | 51 5/1405.85)1976414.2225 917.86 
Mean,|/917.11 2971.38 994.975 
One hundred and fifty feet north-east of the Magnetical Observatory. Locality, same 
as before. 
43, Pittsburgh, Pa., Latitude 40° 32', N.; Longitude 80° 02’, W.; March 22, 1841. 
“72°43'30"| 1 {11h.00m.028.8 1632.2 | 68° |1630.63/2658954,1969| 891.47| 3002.00 | 1005.23 
Locality, “Hogs-back,” three hundred feet, west of Theological Seminary, in Alle- 
eheny-town. Geology, sandstone of the coal measures. 
44, Philadelphia, April 26, 1841. 
71° 59’ | 1 | 14.80m.038.2 |1609.6 , 70° 11607.67|2584602.8289/917.11 
2 2 11 O02 8 /1587.2 | 65 5/1585.95/2515237.4025/918.20 
3 2 45 00 4 {1291.6 | 67 5/1290.84/1666267.9056)916.63 
4 3 16 O38 2 41159.2 | 70 {1158.45)1342006.4025)918.53 
5 38 562 59 6 j1412. 71 8/1410.83)1990441.2889/916.34 
6 4 25 038 2 11406. 67 411405.89|1976526.6921/917.76 
Mean,|917.43 2965.21 993.245 
At twelve hours thirty-seven minutes. Cloudy, calm; clouds becoming thinner. 
45. Trenton, N. J., Latitude 40° 133’, N.; Longitude 74° 40’, W.; April 23, 1841. 
71° 59’ 4 1h.47m.588.8 |1156. 57° (1156.22) 1336844.6884/922.08 
5 2 16 08 2 (1406.8 | 54 4/1407.35)1980634.0225) 120.86 
6 2 51 00 4 1{1402. 54 |1402.'75/1967707.5625|921.87 
Mean,|921.60 2979.60 997.76 
Soil alluvial, with a primitive substratum. Air damp and misty. Place, a woodland 
about three-fourths of a mile north of Trenton, near a streamlet, and just below a deserted 
turnpike road. ‘Time noted by New York meridian. 
46. Newark, New Jersey, Latitude 40° 43’, N; Longitude 74° 10’, W.; April 19, 1841. 
72° 49' 1 |10A.1 m.00s.4 A1640,8 , 49° [1642.96 2699333,9912/878.13 
2 |10 42 O16 1620.4 50 5, 1622.63]2632928.1169/877.11 
8 |I1 11 00 4 1320, | 51 |1820,68]1744195.6624 872.46 | 
4 8 19 08:2 1182, 45 51183.11)1899749.2721 880.64 
5 8 49 02 8 \1439.6 45 jiaaten 2076798.0341 878.13 
6 9 24 O4 4 (1435.6 | 47 5/1437.17/2065486.3524 878.23 
Mean,'878.45 2974.46 995.673 
| 
Time, by the meridian of Philadelphia. 
Locality, “down the neck,” in Morris’s woods, so thick as to exclude the wind, 
which, with a clear sky, blew in strong gusts. Geology, probably sand underlaid 
VOL. IX.—79 
stipes So RE 
