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Article XXX.
On the Laws according to which the Magnet acts upon a Spiral when it is suddenly approached to or removed from it; and on the most advantageous mode of constructing Spirals for Magneto-electrical purposes; by E. Lenz.
From the Mémoires de l'Academie Impériale des Sciences de St. Petersbourg, vol. ii., 1833, p. 427. Read on the 7th of November, 1832
From the great interest which the late discoveries of Faraday in the field of electro-magnetism must awaken in all the natural philosophers of Europe, it is to be expected that we shall soon receive many and various explanations of the momentary action of an electric current on an electrical conductor; and as it is allowed according to Ampère to reduce the action of a magnet entirely to that of circular electric currents, the same may be expected with respect to the action of the magnet upon such a conductor. Up to the present moment we here in the north are only acquainted with the papers of Becquerel, Ampère, Nobili, and Antinori and Pohl; and as none of these authors have occupied themselves with that branch of the subject to which I have directed my particular attention, I hasten to make known as quickly as possible the following contribution to the science of magneto-electrism.
After having repeated Faraday's chief experiments[2], I first proposed to myself to find out in what manner the phænomena of the magnetic action on a spiral suddenly approached or removed might be produced in the easiest and most powerful manner. For this purpose I had to determine what influence
- 1. The number of coils,
- 2. The breadth of the coils,
- 3. The thickness of the wire,
- 4. The substance of the coils,
of the electromotive spirals (i. e. of those which are acted upon by the magnet) had upon the pæhnomenon; and this determination, together with the necessary consequences following from it, are contained in this present memoir.
- ↑ Translated from the German by Mr. W. Francis.
- ↑ In this repetition I obtained the spark beautifully by means of a spiral of a wire 70 feet in length and 0·044 inch thick. The apparatus was formed after the one described by Nobili, so that the horse-shoe magnet (of 22 lbs. lifting power) caused of itself the closing of the current.
