OBSERVATIONS ON 



Dip. 



Epoch of 

 commencing 

 vibration, 

 hrs. min. sec. 



Duration 





Calculated 



of 500 



5-3 



duration 



vibra- 



ii 



at 60°. 



tions. 



B a 





Square of the 

 preceding. 



Horizon- 

 tal inten- 

 sity. 



Total in- 

 tensity : 

 hor. be- 

 ing 1000. 



Total inten- 

 sity : that at 

 Cincinnati 

 = 1000. 



150. MontpeUer, Vt.— Lat. 44° 17' N. Long. 72° 36' W. June 25, 1845. 



75° 16' 15" 



9 27 08 A 

 11 04 52 



1549.6 

 1547.0 



60.0 

 58.0 



1549.60 

 1547.40 



24012601600 



23944467600 



Mean 



755.96 

 752.11 

 754.03 



2965.8 



998.10 



151. Burlington, Vt.— Lat. 44° 27' N. Long. 73° 10' W. June 26, 1845. 



75° 37' 

 Var. 9 22 W. 



10 51 05 A 

 12 28 02 P 



1560.0 

 1556.0 



70.00 



74.75 



1559.00 

 1554.40 



24304810000 



24161593600 



Mean 



746.90 

 745.80 

 746.10 



2999.6 



1003.5 



152. Colximbus, Ohio.— Lat. 39° 57' N. Long. 83° 03' ,"W. July 19, 1845. 



71° 04' 15" 

 Var. 2 29 21 E. 



6 37 01.2 P 



7 06 00.2 



1375.0 

 1368.8 



79.0 

 74.5 



1371.37 

 1367.05 



18806556760 965.23 



18682570250 963.64 



Mean 964.43 



995.66 



153. Cincinnati, Ohio.— Lat. 89° 06' N. Long. 84° 22' W. August 12, 1845. 



70° 29' 27" 



12 59 00.0 

 1 83 03.6 



1350.4 

 1346.8 



79.5 

 81.0 



1348.56 

 1344.31 



18186140736 

 18071693761 



1000 

 1000 



2993.2 



1000 



154. Oxford, Ohio.— Lat. 39° 30' 15" N. Long. 84° 38' W. August 29, 1845. 



71° 10' 

 Var. 4 50 E. 



5 28 58 P 



6 04 00.8 



1366.0 

 1363.0 



74.50 

 78.00 



1364.62 

 1361.44 



18621877444 974.80 



18585188730 971.60 



Mean 973.20 



8005.9 



1005.6 



155. Richmond, la.— Lat. 39° 49' N. Long. 84° 47' W. September 1, 1845. 



71°- 20' 20" 

 Var. 4 52 00 E. 



11 



03 



00.8 A 



1136.4 



94.00 



1138.90 



2 



01 



40.4 P 



1380.0 



89.00 



1377.20 



1 



30 



00.0 P 



1376.4 



92.00 



1372.53 



12857292100 

 18966798400 

 1883838609 

 Mean 



959.06 

 957.08 

 955.96 

 957.37 



2992.1 1002.00 



150. Montpelier, Vt. — Geology : talcose slate, highly inclined. Local attraction evident at the state- 

 house. 



151. Burlington, Vt. — Geology: limestone. 



152. Columbus, Ohio. — Geology (upper silurian?): cliff limestone, horizontally stratified. 



153. Cincinnati, Ohio. — The above observation will give a higher intensity at Cincinnati than was 

 indicated April 23, and this I attribute to an error in the dip, which was taken by a needle known to be 

 imperfect. Compared with the observation of April 23 as 1000, it equals 1002.3. 



154. Oxford, Ohio. — Geology: blue limestone or lower silurian. Showers; some small rain during 

 observations. 



155. Richmond, la. — Done in the garden of Dr. Plummer. A blanket was stretched, to screen the 

 apparatus from the sun ; but it radiated heat so much as to raise the temperature above the surrounding 

 medium. Geology : upper part of the blue limestone (lower silurian) ; horizontally-stratified rocks eight 

 or ten feet below the surface. Clear, but with a disposition to showers. 



