164 Prof. Weber on the Application of Magnetic Induction 



clination I are obtained from the four series of observations 

 B, C, B, E :— 



Tan I. 



6881-27 

 2875^ 



6886-10 

 2875-10 



6889-36 

 2875-10 



6887-98 

 2875-10 



I. 



6°7 19 26 



67 20 18 



67 20 53 



67 20 38 



From the 2ncl to the 12th of August observations were made 

 and calculated in a similar manner four times a day, at 1^, 7^, 

 13^ 19^ by Prof. Weber, Dr. v. Quintus Icilius, M. Eisenlohr 

 and Mr. Hansen. All these gentlemen were accustomed to 

 observations with magnetometers, and the agreement in their 

 several results proved that no other practice is required beyond 

 that which is necessary for all other magnctometric observations. 



The mean inclination deduced from all these observations 

 was for 



Aug. 7, 1852, 67° 19' 43". 



For purposes of comparison it was found necessary to apply a 

 small correction to this result, on account of a slight influence 

 exerted by the magnetometer upon the inductor ; the data for 

 this correction were easy to deter mi nej and after applying it, the 

 inclination for 



Aug. 7, 1852, was 67° 18' 38". 



This result is next compared with others previously made in 

 Gottingen by Humboldt, Forbes and Gauss. Their results were 

 the following : — 



Hence, from Gauss's observations, the mean annual decrease 

 of the inclination in Gottingen for the ten years between 1842 

 and 1852 



= 2' 9"; 



