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 , 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 duration 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 armature 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 cwt., 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 employed for the purpose of moving machines.
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 phænomenon 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.
