540 PROF. HENRY ON THE INFLUENCE OF A SPIRAL CONDUCTOR 
would be much stronger, and assist in destroying the remaining weaker 
magnetism in the other magnet. There would therefore be a moment 
when the magnetism became = 0, and at that moment I expected that 
the armature would be disengaged, and then be attracted to the active 
electro-magnet. However, this interval was of such momentary du- 
ration that the armature remained attached to the passive magnet. I 
then took, instead of the armature of soft iron, a steel magnet of exactly 
the same form and shape, and placed it so that its poles were always 
opposite to the similar poles of the electro-magnets; but even with 
this alteration the same result took place; it also happened when the 
electric current was sent at the same time, but in an opposite direction, 
to the other electro-magnet. As the power of the electro-magnet was 
considerably greater than that of the steel magnet, I could not expect 
to obtain more powerful effects than I had obtained with the soft iron. 
At last I determined to prevent any possible contact between the arma- 
ture and the electro-magnets: this I effected by wrapping the armature 
up in paper, so as always to keep it at a small distance from the poles 
of the magnet. The result was now quite satisfactory. I also enveloped 
the steel magnet in the same way, and it appeared to me that with the 
first-mentioned armature the motion was quicker and more energetic 
than with the latter. If we consider that electro-magnets have already 
been made which were capable of carrying 20 ewt., and that there is 
no reason to doubt that they may be made infinitely more powerful, I 
think I may assert boldly that electro-magnetism may certainly be em- 
ployed for the purpose of moving machines. 
On the Influence of a Spiral Conductor in increasing the In- 
tensity of Electricity from a Galvanic Arrangement of a 
Single Pair, &c. By Professor Henry, of New Jersey, 
as 
In the American Journal of Science for July 1832, I announced a 
fact in Galvanism which I believe had never before been published. 
The same fact, however, appears to have been since observed by Mr. 
Faraday, and has lately been noticed by him in the November number 
of the London and Edinburgh Journal of Science for 1834. 
The phenomenon as described by me is as follows: “ When a small 
* Read before the American Philosophical Society, Feb. 6th, 1835.—This 
has been annexed to the preceding papers as being referred to in them, and as 
a slight notice of it only has appeared in this country: see Phil. Mag. and 
Annals, vol. x. p. 314. 
