AND THE INTENSITY OF MAGNETICAL FORCE. 319 
Princeton, second station, same as above, May 24, 1844, 
Calculated 
duration 
at 60°. 
Duration 
of 500 
Vibrations. 
: | ‘Total intensity, 
Horizontal that at Cincin- 
—— being 1000. 
‘Tempe- 
rature. 
Square of the 
Dip. No. of | Epoch of commencing 
i preceding, 
Needle. Vibrations. 
| 
72°41'16") 4 | 6h.47m.58s.4 Al1180.8 | 57° 1181.03'1394761.0000 884.06 
5 | 7% 20 04 4 [1439.6 | 59 |1439.70.2072736.0600 |880.44 
6 7 54 04 8 {1436.4 | 61 5)14385.93)2061435.4929 /878.60 
Mean, |/8'79.52 990.53 
The above, by reducing the result of No. 4 by the constant .00285, makes 884.06. — 
2.52 = 881.51, and including this with the results of Nos. 5 and 6, as above, gives as 
a mean for total intensity 991.40, instead of 990.53, as above. 
Princeton, third station, Rocky Hill, May 24, 1843. 
This station is more than a mile from the town, and is ata ridge of trap, rising gradually 
from the shale below. 
New Brunswick, New Jersey, Latitude 40° 30’, N.; Longitude 74° 25’, W.; May 4, 1844; a quarter of a mile 
south of the city, in a little ravine. 
72°43'13"| 4 | 3h.34m.02s. P/1183.2 | 77°0)1181.9 |1396887.61 (882.71 
5 |4 06 08 6 [1440.4 | 77 5)1488.64/2069685.0496/881.69 
6 | 4 38 00 0 [1435.6 | 75 5)1433.64/2055323.6496)881.21 
_Mean,|/881.45 | 994.64 
I considered the above an unexceptionable locality, and that the elements represented the 
mean of the neighbourhood. ‘The rock is a shale not far below the surface. 
Columbia College, New York City, Latitude 40° 42’, N.; Longitude 74° 01’, W.; April 27, 1844. 
72°42'38"| 4 |124.389m.015.2 Pj/1180.8 | 55°0)1181.18 1395186.1924/883.79 
5 1 06 04 4 {1488.4 | 53 5/1439.05/2070864.9025/881.24 
6 1 37 04 0 {1481.6 | 50 0/1432.86/2053087.7796|882.12 
Mean,|881.68 994.35 
Diluvial sand, of great depth, superimposed on gneiss. 
Asylum for the Insane, near Harlaem, eight miles north of New York; April 26, 1844. 
72°41'40"| 4 |12A.52m.515.6 P|1182.8 | '78°5|1181.40)1895705.76 |883.46 
5 1 23 09 2 {1441.2 | 79 0/1439.30/2071584.49 (880.93 
6 1 52 02 0 11486.6 | 82 0/1433.6212055266.3044/881.23 
Mean,'881.08 | 992.40 
Prismatic gneiss rock, near the surface. 
Newark, New Jersey, Latitude 40° 48', N.; Longitude '74° 10’, W.; April 29, 1844; at Mrs. Morris’s Garden, 
in Washington place. 
72°50'15"| 4 | 8h.21m.00s.8 |1186.8 | 61°5|1186.80/1408494.24 (875.44 
5 |8 52 00 0 {1444.4 | 61 5/1444.40|2086291.360 [874.72 
6 9 25 10 0 {1440.4 | 63 0/1440.00)2073600.0 873.44 
Mean,|874.08 992.40 
Deep alluvium, superimposed on new red sandstone. 
VOL. IxX.——-84 
