AND THE INTENSITY OF MAGNETICAL FORCE. 301 
Locality, north-east of the Washington monument, and in the south-east corner of the 
woods. 
51, Baltimore, St. Mary’s College, April 28, 1841. 
F 3 ‘ Duration |, : Caleulated) : =2 | 2 ‘ 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. = being 1000. |nati being 1000. 
71°39'11") 1 3/.30m.028.8 P}1598. 68° 8)/1596.31 2548205.6161| 930.21 
2 4 07 O1 2 |1574.8 | 65 |15'73.66/2476405.'7956) 932.58 
3 4 44 05 4 |1279.6 | 63  |1279.38/1636813.1844) 933.12 | 
4 5 17 02 0 |1150. 64 5/1149.66 1321718.1156 932.63 | 
5 5 48 02 8 /|1400. 59 |1400.1 /1960280.01 | 930.43 | 
6 6 15 58 4 |13894. 54 5)1894.67/1945104.4089) 932.58 
Mean,| 931.92 2953.82 991.399 
Locality, in the midst of the botanical garden of St. Mary’s College. Clear, fine, 
gentle north-west wind. Substratum, primitive rocks. Although Howard’s woods and 
St. Mary’s College are less than a mile apart, the local differences are very considerable, 
and might throw some degree of discredit on the results, were it not that the facts are too 
well established by independent observers. At both the above localities, Mr. Nicollet 
made observations, to determine the dip, on the same day, and nearly on the same hours, 
with a similar apparatus, manipulating, at my request, in the mode which I had adopted. 
The results were remarkably coincident, as have been others at the same localities. The 
results are contrasted below :— 
AT HOWARD’S WOODS, ST. MARY’S COLLEGE. 
By Professor Bache, August 24, 1840, dip = 71° 34’ 4” Professor Bache did not observe at this place. 
By Professor Locke, April 28, 1841, 71 84 3 By Professor Locke, April 28, 1841, dip = 71° 39’ 2” 
By Mr. Nicollet, April 28, 1841, 71 34 9 By Mr. Nicollet, April 28, 1841, 71.88 6 
By Major Graham, June 10, 1841, 71 31 9 By Major Graham, June 11, 1841, 71. 83-8 
Those who endeavour to maintain that magnetical dip cannot be very nearly measured 
by good ‘instruments, carefully used, will find it difficult to account for such a coinci- 
dence as is exhibited above. Other localities in the neighbourhood of Baltimore will 
probably exhibit equal, or perhaps greater, differences than the above. 
Bristol, Pennsylvania, Latitude 40° 09’, N.; Longitude, 74° 47’, W.; April 14, 1841, 
Dip 72° 27 30”. No experiments were made here to ascertain intensity; but, in 1842, (sce the series for that 
year,) that point was determined. 
Locality, Professor Vanuxem’s, on the bank of the canal. Geology, deep diluvial 
gravel and clay (?) underlaid by primitive rocks. It will be observed that the dip here is 
greater than at Philadelphia or Trenton, 
V. SERIES, FOR 1842, CINCINNATI TO CAMBRIDGE, (MASSACHUSETTS.,) 
The intensities at Cincinnati, May 8, 1841, being assumed as unity. 
52. Cincinnati, March 31, 1842. 
~70°20'20") 1 | 12.40m,045,8 A Bias very Satte 
10 28 024 {1686.8 | 52° (1538.2 '2366059.24 1001.82 
10 58 02 1516.4 | 54 |1517.7 2303413.29 |1002.62 
11 41 00 1236. 54 5/1286 3 /1528684.96 | 999.18 
12 22 02 4P)1350.8 | 55 5)1351.02 1825741.44 999.00 
12 61 59 2 11846.4 ' 67 (1846.75 1813735.5625 1000.13 
Mean,'1000.54! 2973.72 | 996.19 
oakwe 
