dev elopement of magnetical properties in steel and iron, &c. 213 
periment No. XIII, on a new wire by the compound process, 
occasioned in this wire, of only 145 grains weight, a lifting 
power of 265 grains. 
3. The increased magnetic energy developed by the use 
of larger bars of iron (a fact indeed which it was reasonable 
to expect) is quite satisfactory in all the comparative experi- 
ments. The long wire S t ii, by the small apparatus was made 
to lift between 326 and 389 grains, being the highest effect 
produced on it [Experiment No. VII.]] ; but on applying it to 
the large apparatus, its lifting power was at length aug- 
mented to 662 grains. [Experiment XVI.] And by the small 
apparatus, the highest power that could be given to the wire 
S t i, was a capability of lifting a weight of 345 grains [Ex- 
periments II, III, IV,] ; but on using the large apparatus, 
the same wire [Experiment XIV.] was eventually made to 
lift 669 grains, being abo we four times its own weight. This 
was the highest effect produced. The advantage, however, 
of the large apparatus, was the most striking in the case of 
untempered wires. An untempered wire, S u i, had its lifting 
power, by the first apparatus, with difficulty raised to nearly 
70 grains, [Experiment I.] whilst a similar, but somewhat 
shorter wire, Sz/ iii, was, by the use of the large apparatus, 
readily made to lift 246 grains ; and by continuing the pro- 
cess on several different days, its power was at length 
increased to 6 02 grains. [Experiment XV.] 
4. It would appear from experiments IV. and XV, that in 
the use of any one apparatus there is a limit to the power 
which it is capable of developing ; whereas, from the great 
augmentation of effect obtained by the use of a larger appa- 
ratus, it becomes probable, that were iron rods sufficiently 
