Terrestrial Magnetism. 



155 



In the above observations, it appears that each needle, while it 

 gave by repeated observations results consistent with itself, dif- 

 fered obstinately from the other to the amount of near four min- 

 utes. 



JYo. 14. Princeton, Indiana, Lat. 38° 23' JV., Lon. 87° 30' W. Sept. 16, 1840. 



