284 Mn Barlow on the secondary deflections deduced 
vibrations made by each in a minute when in their natural 
magnetic state, was eighteen. No. 1. was left in that state. 
No. 2. was deteriorated in its northern branch; No. 3. in its 
southern; after which No. 2. made only 11 vibrations in a 
minute, and No. 3. 12 vibrations in the same time. With 
these needles the experiments were conducted as follows. 
The ball was raised till its centre was 10 inches above the 
pivot of the needle, and the latter placed at 1 3% inches from 
the centre of the table, making the distance between the 
pivot and the centre of the ball 16*8 inches, which distance 
was preserved in all the experiments. The box containing 
the needle was placed in the situation above mentioned, first 
north of the ball, then N. 20° E, N. 40 0 E. and so on all 
round to the north again. And in each of these positions 
the deviation of each needle was successively registered, the 
results being as in the first division in the following table. 
Precisely a similar set of observations were made with the 
centre of the ball 10 inches below the pivot of the needle, as 
in the 3d division of the table ; and lastly, a like set were 
obtained with the centre of the ball level with the pivot of 
the needle, the latter in this case being placed at the whole 
distance 16 8 from the centre of the table. 
