150 



Terrestrial Magnetism. 



tained by the two needles seldom differed more than one minute, 

 I deem it essential to correct the error by copying below the en- 

 tire minutes of the observation at that place. 



I will here add some observations made on the dip in Ohio, 

 Indiana and Kentucky, within the last three months. The re- 

 gion over which these observations have been extended, embra- 

 ces rather more than two degrees of latitude and three degrees of 

 longitude. Dip, intensity, and declination, were all made the 

 objects of inquiry, but I here communicate only what relates to 

 the dip, especially to show the close agreement of the results of 

 the two different needles. 



JVo. 1. Piqua, Ohio, Lai. 40° 06' A'., Lon. 84° 10' W. Aug. 22, 1840. 



