230 PECULIARITIES IN THE MAGNETISM 
scale than the original ones, I was desirous of 
repeating them, and also that with the hollow tube, 
on masses of iron much larger than those I had 
previously employed. Through the favour of 
Mr. Richard Roberts, to whom I made known my 
desire of carrying on these inquiries on a larger 
scale than [ had any opportunity of pursuing them 
before, I have been enabled to make the neces- 
sary experiments under the best possible advan- 
tage; and I am happy to say, with the most 
satisfactory results. 
54. The experiments were made at the Ad/as 
works, belonging to Messrs. Sharp and Roberts, 
engineers, on Saturday the 24th instant, in the 
following manner. 
55. The first series of experiments were with 
an iron tube, two feet long, and two inches in 
external diameter; the thickness of the metal 
being about two-tenths of an inch. The tube, 
when under examination, was placed in the line 
of magnetic dip; having its lower extremity 
resting in a cavity, purposely made, in a fire brick, 
and its upper extremity leaning against a tall 
brick tile, placed in a vertical position for the 
purpose. A magnetic compass, whose needle is 
