developement of magnetical properties in steel and iron , &c. l 99 
diameter. The weight of the former was 8 lbs. and of the 
latter 2 ylbs. The end of the larger rod ( I i* ) , designed to 
be kept upward, was made conical, with the view of con- 
centrating its magnetic force ; but this was truncated at the 
diameter of a quarter of an inch, and a shallow hole drilled 
in the centre for steadying the steel wires when hammered, 
the lower ends of which wires were rounded into a blunt 
point, so as to fit the depression in the top of the iron rod. 
The lower end of the shorter rod ( I ii ) , was constructed in a 
similar manner. 
As I could not hammer this conical extremity of the 
large iron rod without destroying its form and face, I made 
use of another iron rod (I iii), corresponding in size and 
weight with the rod (I ii ) , but having its lower extremity 
hollowed like a cup, to fit upon the conical termination of 
the larger rod (I i. ) The larger rod was generally hammered 
before each experiment through the medium of this shorter 
rod, ( I iii ) , which not only served to preserve the other rod 
from injury, but at the same time tended to augment its 
magnetism. 
In experiments with this apparatus, then, after eliciting 
some magnetic energy in the rod Ii, by hammering it in the 
way just described, the steel wire intended for receiving the 
magnetism was placed between the two rods, with the conical 
* To prevent circumlocution, I have distinguished the rods and wires used in 
the following experiments by the initial letters descriptive of the substance of 
which they were composed, connected with a number to distinguish the different 
bars and wires of the same quality. Thus I, signifies an iron rod or bar ; and S, 
a steel bar or wire ; S u, steel untempered, or in the state in which the wire was 
drawn ; and S t, steel tempered, or softened by heating to redness, and slowly 
cooled. 
