MAGNETIC DIPS IN THE UNITED STATES. 



109 



Magnetic Dip at Washington City. Latitude 38° 53' N.; Longitude 5/t. Bm. W. 

 Place of observation the yard in front of the capitol. 



Date. 





Hour. 



Needle. 



No 



Readings. 





Dip. 



1839, Sept. 



25th, 



3—5, P. M. 



No. 1, 





40 



7r 



' 20'.9 









No. 1, poles reversed, 





40 





14.5 









Mean of No. 1, 





80 





17.7 









No. 2, 





40 





26.4 









No. 2, poles reversed, 





40 





23.7 









Mean of No. 2, 





80 





25.1 









Mean of both needles. 





160 



71 



21 .4 



Magnetic Dip at Pittsburgh, Pennsylvania. Latitude 40° 32' N.; Longitude 5h. 20m. W. 

 Place of observation an open yard on the opposite side of Alleghany river. 



Date. 





Hour. 



Needle. 



No 



Readi 



ngs. 





Dip. 



339, Sept. 



30th, 



9— 11, A.M. 



No. 1, 





40 





72' 



' 44'.5 









No. 1, poles reversed. 





40 







39.3 









Mean of No. 1, 





80 







41 .9 









No. 2, 





40 







34.3 









No. 2, poles reversed. 





40 







37.6 









Mean of No. 2, 





80 







35.9 









Mean of both needles, 





160 





72 



38.9 



Magnetic Dip at Beaver, Pennsylvania. Latitude 40° 44' N.; Longitude 5h. 22m. W. 

 Place of observation on the bank of the Ohio, near Beaver bridge. 



Date. 



Hour. 



Needle. 



No 



Readings. 





Dip. 



1839, Oct. Ist, 



81—10^, A. M. 



No, 1, 





40 



72 



' 34'.9 



(C it (( 





No. 1, poles reversed. 





40 





40*6 



(( (( (( 





Mean of No. 1, 





80 





37.8 



(( a <( 





No. 2, 





40 





40.0 



(( (( t( 





No. 2, poles reversed, 





40 





45.6 



(( a a 





Mean of No. 2, 





80 





42.8 



(( (t (< 





Mean of both needles, 





160 



72 



40.3 



VII. — 2 c 



