OBSERVATIONS OF THE MAGNETIC DIP IN THE UNITED STATES. 185 
however, that these observations are sufficient to furnish the Dip with an uncertainty not 
exceeding five minutes. If we take a mean of all the observations without distinction, 
we obtain for a result 72° 57’.8. If we reject the readings which differ most from the 
mean, we obtain for a result 72° 58’.6. The latter result is, I think, to be preferred; but 
either result indicates that the Dip of the needle at Hudson has increased since 1844. 
The following are a few additional observations made by myself in the vicinity of Hud- 
son: 
Tallmadge, Lat. 41° 7’, Long. 81° 25’ West, near the coal mine. 
Date. Hoour. PoLaRIty. No. READINGS. Dir. 
1842, Sept. 3. 11—12 M. Mark up. 40 72° 54.0 
@ & WG Mark down. 40 51.1 
6 ce 6G Mean result. 80 5.25 
North Akron, Lat. 41° 5’, Long. 81° 30’ West, a quarter of a mile east of the village. 
1842, Sept. 5. 2—3 P. M. Mark down. 40 72 48.1 
“6 GB = cc Mark up. 40) 56.4 
GG GG “ Mean result. 80 52.2 
Cuyahoga Falls, Lat. 41° 9’, Long. 81° 27’ West, a quarter of a mile south-east of the 
village. 
1842, Sept. 6, 10—11 A. M. Mark up. 40 72 $2.1 
6 6 “c Mark down. 40 49.6 
“ “ “ Mean result. 80 50.9 
6 66 11—12 M. Mark down. 40 50.3 
“ ee G Mark up. 40 54.5 
“ “ “ Mean result. 80 52.4 
GG GG Mean of both series of observations. 160 72 61.6 
Franklin, Lat. 41° 11’, Long. 81° 20’ West. 
1842, Sept. 8, 45 P. M. Mark up. 40 72 «55.4 
G G3 cs Mark down. 40 51.2 
ce Gs bb Mean result. 80 53.3 
Rootstown, Lat. 41° 7’, Long. 81° 14’ West. 
1842, Sept. 9, 1—2 P. M. Mark down. 40 72 51.3 
Gs 6G 6 Mark up. 40 68.2 
Gs 66 ¢¢ Mean result. 80 59.7 
Paris, Lat. 41° 11’, Long. 81° 2’ West, near the village. 
