MAGNETIC SURVEY OF GREAT BRITAIN. 



159 



In the following table are collected the observations made 

 with these needles in London, in July 1838, and in December 

 of the same year, for the double purpose of examining the 

 steadiness of their magnetism in the interval, — during which 

 they had been employed in the observations in Scotland now 

 under notice, find in a similar series in Ireland, — and of deter- 

 mining the angle of deflection in London as the base station of 

 both series. 



Table LIX. 



On comparing the observations with both needles in July 

 and in December, we may conclude that the magnetism of 

 both had remained unchanged during the interval ; the small 

 differences are only such as frequently occur on different days ; 

 they are, moreover, in different directions, and so far will com- 

 pensate each other in the final deduction. 



In Table LX. are comprised Captain Ross's observations 

 with these needles at nine stations in Scotland and the north 

 of England. 



