M. Matteucci on the Electrk Discharge of the Jar. 37 



"*'niuch more evident manner when the fixed conductor or the 

 illbveable conductor is in communication with the conductor 

 oF the electrical machine. Lastly, if the fixed conductor be 

 electrified with sparks, the moveable conductor is successively 

 attracted and repelled. These phaBnoniena are veiy easily 

 explained by the ordinary attractions and repulsions of elec- 

 ' trifled bodies, in presence of bodies in the natural state. I 

 only wished to try these experiments with my apparatus, in 

 order to see what part it might have in the phaenomena which 

 I am about to describe. The two conductors are arranged in 

 such a manner as that the discharge should penetrate them in 

 opposite directions. The distance between the two conductors 

 was from ten to fifteen up to thirty millimetres. I began by 

 observing the moveable conductor with a telescope ; but this 

 was useless, for the movements of repulsion which take place 

 in the moveable conductor at the moment of the discharge 

 are so great that they may be observed with the unassisted 

 eye. On passing the current along the two conductors in the 

 same direction, the moveable conductor was also seen, and in 

 a very distinct manner, to fall upon the fixed conductor at the 

 moment oFthe discharge. Thus we may admit, without any 

 kind of doubt, that the fundamental law of Ampere, oFthe at- 

 traction of currents of the same direction, and of the repulsion 

 of currents of opposite direction, holds good in regard to the 

 discharge of the jar under the same circumstances. 



I shall lastly add, that I repeated my experiments on the 

 induction of the discharge of the jar {Annales de Chimie et de 

 Physique, 3rd series, t. iv. Feb. 1 842.), by passing the discharge 

 of the battery through the wire oF a plane spiral in presence 

 oF a similar spiral, the two extremities oF which are united with 

 the ends of the wire oF a galvanometer. At whatever distance 

 the two spirals are, the current oF induction, which continu- 

 ally diminishes in proportion as the distance increases, al- 

 ways passes in the same direction as the current oF the jar. 

 cesses oF magnetizing to ascertain the direction oFthe current 

 I lay a stress on this result, because, when employing the pro- 

 oFinduction, we sometimes find this result, sometimes the con- 

 trary, according to the distance oFthe two spirals and the ten- 

 sion oF the discharge. When the current oF induction is made 

 to act on another spiral, whose extremities communicate with 

 the galvanometer, the current oF induction oF the second order 

 which is obtained passes in the contrary direction to the in- 

 ductor current. These are the results described in my me- 

 moir already cited, — results which I have just now had occa- 

 sion to veriFy. 



