ELECTRO-MAGNETISM AS A MECHANICAL POWER. 533 



upon tlie latter. But an adhesion whicli continued after the ces- 

 sation 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 jjoint 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 ordinaiy 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 de- 

 grees acquires the maximum of velocity which the energy of the cur- 

 rents 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*. 



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 suggestsf . 



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 deci- 

 metre in length and a centimetre and a half in diameter ; these are sur- 

 rounded 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 2^ 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 



* 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-mag- 

 netic 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. 



t The Chev. Avogrado and the Chev. Bidone, who have successively seen 

 the apparatus in motion, did not dissemble the agreeable sui-prise which tliey 

 experienced, not merely from the novelty of the fact, but also from the reflec- 

 tions suggested by the general relations which may connect this simple residt 

 with the progress of physics and mechanics. 



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