MAGNETIC DIP IN THE UNITED STATES. 295 



Date. 



Hour. 



Needle. 



No 



Readings. 



Dip. 



, Sept. 6, 



5—61, P. M. 



No. 2, 





40 



73° 21'.8 



<( 



(( 



No. 2, poles reversed, 





40 



25.1 



(( 



i( 



Mean of No. 2, 





80 



23.4 



(( 



(i 



Mean of both needles. 





160 



73 23.2 



No. Readings. 





Dip. 



40 



73 



° 30'.6 



40 





40.7 



80 





35.6 



40 





19.9 



40 





48.3 



80 





34.1 



160 



73 



34.9 



Magnetic Dip at Blue Mounds, Wisconsin. Latitude 43° 0' N.; Longitude 89° 36' W. 

 Place of observation near Mr. Ebenezer Brigham's. 



Date. Hour. Needle. 



1841, Sept. 7, 12—2, P. M. No. 1, 



No. 1, poles reversed. 

 Mean of No. 1, 

 No. 2, 



No. 2, poles reversed, 

 Mean of No. 2, 

 Mean of both needles, 



In fording a creek, this morning, near Mineral Point, the compass got wet. 

 It was carefully dried as soon after as possible, and is thought to have expe- 

 rienced no serious injury. This is probably the cause of the inequality in the 

 weight of the arms of No. 2, as shown in the last observation. Nevertheless, 

 the mean results of the two needles accord as well as usual. 



Magnetic Dip at Madison, Wisconsin. Latitude 43° 3' N.; Longitude 89° 11' W. 

 Place of observation eighty rods south-east of the capital. 



Date. Hour. Needle. 



1841, Sept. 8, 10—12, A. M. No. 1, 



" " No. 1, poles reversed, 



" «« Mean of No. 1, 



" " No. 2, 



" '• No. 2, poles reversed, 



" " Mean of No. 2, 



" " Mean of both needles, 



Observations repeated near the same Place. 



Date. Hour. Needle. I 



1841, Sept. 8, 1—3, P. M. No. 1, 



" •' No. 1, poles reversed, 



" " Mean of No. 1, 



" " No. 2, 



VIII. — 3 z 



No. Readings. 



Dip. 



40 



73° 67'.6 



40 



59.0 



80 



63.3 



40 



77.8 



40 



54.2 



80 



66.0 



160 



74 4.7 



"So. Readings. 



Dip. 



40 



73° 62'.6 



40 



73.3 



80 



68.0 



40 



57.1 



