18 





OBSERVATIONS OF THE 









Date. 



Hour. 





Needle. 



No. 



Readings. 



Dip. 



1841, Aug. 12, 



4-1, P. 



M. 



No. 2, 





40 



73° 3 .4 



<( 



(( 





No. 2, poles reversed. 





40 



3.9 



<( 



i< 





Mean of No. 2, 





80 



3.7 



(( 



(t 





Mean of both needles. 





160 



73 4'. 3 



I have now made four observations for the dip near Cleveland. First, upon 

 the north side of the city; then upon the south side; next upon the west; and, 

 last, upon the east. The dip at Cleveland, according to observations made in 

 the neighbouring towns, should be 73° 4'.0. The station error, then, of the 

 first observation was + 22'. 0; of the second, + 8'.0; third, + 12'. 3; fourth, 

 + 0'.3. Corresponding anomalies have been detected in observations for the 

 variation of the needle in this vicinity. 



Magnetic Dip at Monroe, Michigan. Latitude 41° 55' N.,- Longitude 83° 28' W. 

 Place of observation a half mile north of the court house. 



Date. 





Hour. 





Needle. 



No. 



Readings. 



] 



Dip. 



841, Aug. 



14, 



2— 4, P. 



M. 



No. 1, 





40 



73= 



' 15'.9 











No. 1, poles reversed. 





40 





22.7 











Mean of No. 1, 





80 





19.3 











No. 2, 





40 





19.2 











No. 2, poles reversed. 





40 





18.4 











Mean of No. 2, 





80 





18.8 











Mean of both needles, 





160 



73 



19.0 



Magnetic Lip at Fpsilanti, Michigan. Latitude 42° 14' N.; Longitude 83° 38' PF. 

 Place of observation sixty rods east of the rail-road depot. 



Date. 



Hour. 





Needle. 



No. Readings. 



Dip. 



1841, Aug. 16, 



7—9, A. 



M. 



No. 1, 



40 



73° 24'. 1 









No. 1, poles reversed, 



40 



15.5 









Mean of No. 1, 



80 



19.8 









No. 2, 



40 



17.4 









No. 2, poles reversed, 



40 



18.1 









Mean of No. 2, 



80 



17.8 









Mean of both needles. 



160 



73 18 .8 



