68 



OBSERVATIONS TO DETERMINE THE MAGNETIC DIP 



The preceding trial appears to me to justify confidence in the needles em- 

 ployed, and to give additional value to my former observations. 

 The following observations were made in the usual manner : 



Magnetic Dip at Hudson, Ohio. Latitude 41° 15' N.; Longitude 81° 26' W. 





Date. 





Hour. 



Needle. 



No. 



Readings. 





Dip. 



840 



, April 



15th, 



8^— 11, A.M. 



No. 1, 





40 



72= 



' 50'.3 











No. 1, poles reversed. 





40 





44.1 











Mean of No. 1, 





80 





47.2 











No. 2, 





40 





69.5 











No. 2, poles reversed, 





40 





49.0 











Mean of No. 2, 





80 





59.2 











Mean of both needles. 





160 



72 



53.2 



Magnetic Dip ai Aurora, Ohio. Latitude 41° 20' N.; Longitude 81° 20' W. 

 Place of observation thirty rods north-west of the Presbyterian church. 



Date. 





Hour. 



Needle. 



No. Readings. 





Dip. 



1840, Sept. 



8th, 



9—11, 



A.M. 



No. 1, 



40 



72< 



'51'.0 





(( 







No. 1, poles reversed. 



40 





48.4 





(( 







Mean of No. 1, 



80 





49.7 





<( 







No. 2, 



40 





57.3 





a 







No, 2, poles reversed, 



40 





65.1 





(( 







Mean of No. 2, 



80 





61 .2 





(( 







Mean of both needles, 



160 



72 



55.5 



Magnetic Dip at Windham, Ohio. Latitude 41° 15' N.; Longitude 81° 3' W. 

 Place of observation fifty rods north of the Presbyterian church. 



Date. 





Hour. 



Needle. 



No. Readings. 



Dip. 



1840, Sept. 



8th, 



3—5, 



P.M. 



No. 1, 



40 



72° 57'.2 



(( (( 









No. 1 , poles reversed. 



40 



59.7 



(( (( 









Mean of No. 1, 



80 



58.5 



<( (< 









No. 2, 



40 



73 14.9 



(( (( 









No. 2, poles reversed. 



40 



1.7 



(( (( 









Mean of No. 2, 



80 



8.3 



4L (C 









Mean of both needles. 



160 



73 3.4 



