Scientific Memoirs/1/Note on the Application of Electro-Magnetism as a Mechanical Power

Note on the Application of Electro-Magnetism asa Mechanical Power; by I. D. Botto, Professor of Natural Philosophy in the Royal University of Turin.

From the Bibliothèque Universelle, &c., vol. lvi. Geneva, (1834, vol. ii. p. 312. July.)

The remarkable energy with which the magnetic action is developed in soft iron by induction from electricity in motion is well known.

The possibility of the application of this new power to machines possessing some interest, I have decided on publishing the results which I have obtained relating to this subject[1].

The mechanism which I have employed consists first of a lever put in motion (in the manner of a metronome) by the alternating action of two fixed electro-magnetic cylinders exerted on a third moveable cylinder connected with the lower arm of the lever, the upper arm of which maintains a metallic wheel, serving in the ordinary way as a regulator, in a continuous gyratory motion.

The apparatus was so disposed, that, the axes of the three cylinders being perfectly equal and situated in the same vertical plane perpendicular to the axis of motion, the oscillating cylinder placed itself by one of its extremities alternately in contact with and in the direction of, each of the two other cylinders, stationed at the limits of its excursions; and each time, at that very instant, the direction of the magnetizing current in its spiral was changed, the remainder of the circuit preserving the same direction, so as to produce poles of the same name in the fixed cylinders, at the two extremities facing the moveable cylinder. The change of direction which has just been mentioned is obtained by means of the known mechanism of the bascule, the communications of which are interchanged by the motion of the machine itself.

It is evident that from this arrangement the middle cylinder must undergo corresponding alternations of attraction and repulsion, by the effect of which the apparatus is set in motion, as it were by itself, and maintains itself in action by the œconomy of the magnetic forces which animate it, and which are produced by the electric currents.

I endeavoured to operate without the spiral of the middle cylinder, and by causing the two fixed cylinders magnetized alternately to act upon the latter. But an adhesion which continued after the cessation of the magnetizing currents then contributed to diminish the mechanical effect; whilst in the preceding arrangement the adhesion not only ceased, but to a certain point changed to repulsion, with the same rapidity with which the current, scarcely interrupted an instant by the action of the bascule, precipitated itself (the communication being inverted) into the middle spiral, in a direction contrary to its original one, resuming its ordinary course in the two other spirals.

The motion of the lever and of the regulator, resulting from this arrangement, is perfectly free; at first rather slow, it soon and by degrees acquires the maximum of velocity which the energy of the currents producing it allows of,—a velocity which is afterwards maintained equal to the intensity of the current itself, and as long as the latter remains in action[2].

I shall say nothing at present respecting some observations which I have on this occasion collected, upon the employment of different acid and saline solutions, and of sea water.

It is not without especial interest that we contemplate these new effects of a force developed in so singular a manner from the masses of bodies; and it is difficult not to be carried away by flattering anticipations respecting the ulterior applications which the acquisition of this mysterious motive force suggests[3].

The dimensions of the apparatus which has just been described are small, and such as the current produced by fifteen elements of nine square inches can put in motion. The electro-dynamic cylinders, which principally determine the limits of the mechanical effect, are one decimetre in length and a centimetre and a half in diameter; these are surrounded by a wire coiled in a spiral, the length of which is 40 metres, and half a millimetre in diameter. The lever is of wood; the upper and lower arms are respectively 35 and 7 centimetres long; the amplitude of its oscillations is 15°. Lastly, the regulator weighs 2½ kilogrammes; and the total weight of the mechanism is about 5 kilogrammes.

Considerations which readily presented themselves regarding the relations between the maximum of the magneto-mechanic effect of the apparatus and the dimensions of its different parts, have made me think of substituting for the cylindrical form the ordinary U form of electro-magnetic bars, and of augmenting within certain limits the number and magnitude of these pieces, as well as the length of the spirals.

But not having arrived at the termination of my experiments on this subject, I confine myself for the present to pointing out the above-mentioned facts, which I have thought proper to make known, not only as interesting to science, but also because the study of the new class of effects with which it is connected may be considered as fertile in useful consequences in a physico-mechanical point of view[4].

  1. I ought to state, that the hope of giving a greater extension to my observations, and also the necessity of absenting myself from Turin, have caused me to defer the publication of the facts which I announce, although I should have done so at the end of June. But I have been obliged to decide respecting it, having seen in the last number of the Piedmontese Gazette, that M. Jacobi of Königsberg has succeeded in obtaining a phænomenon of continuous motion by the intervention only of the electro-magnetic power.
  2. There is a great analogy, both with regard to the general arrangement of the apparatus and the nature of the motive power, between the electro-magnetic apparatus of M. Botto, and the electrical clock of M. Zamboni, described in the Bibl. Univ., t. xlvii. p. 183. (1831). It will be recollected that Zamboni's clock is put in motion by a pendulum, alternately attracted and repelled by the poles of two of the dry piles which bear his name.—A. de la Rive.
  3. The Chev. Avogrado and the Chev. Bidone, who have successively seen the apparatus in motion, did not dissemble the agreeable surprise which they experienced, not merely from the novelty of the fact, but also from the reflections suggested by the general relations which may connect this simple result with the progress of physics and mechanics.
  4. The apparratus mentioned in this Note was constructed by M. Jast, mechanician of the Royal University of Turin, who executes with the same success and the same accuracy all other kinds of philosophical instruments.