294 



OBSERVATIONS OF THE 



Observations repeated Jive Sods West of last Station. 



Date. 



1841, Sept. 2, 



Hour. 



101—12 



, A. M. 



Needle. 



No. Readings. 



Dip. 



No. 1, 



40 



72° 47'.6 



No, 1. poles reversed, 



40 



50.2 



Mean of No. 1, 



80 



48.9 



No. 2, 



40 



45.9 



No. 2, poles reversed, 



40 



46.3 



Mean of No. 2, 



80 



46.1 



Mean of both needles, 



160 



72 47.5 

 72 47.7 



Mean of 320 readings with both needles, 



Magnetic Dip at Galena, Illinois. Latitude 42^ 28' iV".; Longitude 90° 13' W. 

 Place of observation on the hill back of the town. 



Date. 



Hour. 





Needle. 



No 



Readings. 



Dip. 



1841, Sept. 4, 



8—10, A. 



M. 



No. 1, 





40 



72° 64'.4 









No. 1, poles reversed, 





40 



59.1 









Mean of No. 1 , 





80 



61 .8 









No. 2, 





40 



61 .4 









No. 2, poles reversed, 





40 



61 .7 









Mean of No. 2, 





80 



61 .6 









Mean of both needles, 





160 



73 1 .7 





Observations 



repeated four Rods Last of last Station. 





Date. 



Hour. 





Needle. 



No. 



Readings. 



Dip. 



1841, Sept. 4, 



10—12, 



M. 



No. 1, 





40 



73° 1'.3 









No. 1, poles reversed, 





40 



5.6 









Mean of No. 1, 





80 



3.5 









No. 2, 





40 



2.5 









No. 2, poles reversed, 





40 



0.7 









Mean of No. 2, 





80 



1.6 









Mean of both needles, 





160 



73 2.5 



Magnetic Dip at Mineral Point, Wisconsin. Latitude 42° 51' N.; Longitude 89° 58' W. 

 Place of observation eighty rods west of the Franklin House. 



Date. 

 1841, Sept. 6, 



Hour. 

 5—6^, P. M. 



Needle. No. Readings. Dip. 



No. 1, 40 73° 26'.0 



No. 1, poles reversed, 40 20.2 



Mean of No. 1, 80 23 .1 



