Intelligence and Miscellaneous Articles, 539 



would not take place with the same facility, the sparks would be 

 less brilHant, and the current would acquire a smaller development. 



A very efficacious mode of diminishing the tension is to have 

 recourse to the well-known properties of the Leyden jar, and other 

 apparatus founded on the same principle. A condenser is formed of 

 two leaves of tin in juxtaposition, but separated and insulated from 

 one another by a layer of varnish, and each of the leaves put into 

 communication with each extremity of the inductive wire ; the points 

 of attachment must be on both sides of the point of interruption 

 when the sparks are produced. Then the two electricities, before 

 arriving at the point of interruption, spread over the two surfaces 

 of the tin, where they lose their tension to a great extent, in conse- 

 quence of the mutual influence exercised across the isolating layer 

 of varnish. 



When the condenser presents a sufficient surface (5 or 6 square 

 decimetres), the light is seen immediately to become weakened at 

 the point of interruption, whilst the machine acquires a remarkable 

 increase of energy ; the poles then give stronger sparks and at a 

 greater distance than before. The condenser may be conveniently 

 placed in a horizontal position, a little above the electro-magnet, 

 and sustained by four glass supports. With this addition, which is 

 very easily made, not only does the machine give more electricity, 

 but it also continues longer in regular action, because the surfaces 

 of the breaker are no longer exposed to the action of the very intense 

 f^parks which change them so rapidly. 



An arrangement invented by M. Sinsteden, in which the principle 

 fof condensation has been employed to obtain stronger discharges with 

 inductive machines, has only an apparent analogy with the method 

 which I here indicate ; the principle and the effects of the two 

 methods being, in reality, very different. In fact, it is the electricity 

 developed in the second wire, the inductive wire, which is modified 

 by M. Sinsteden, so as to cause more brilliant sparks ; but these 

 stronger discharges are not accompanied by an augmentation of 

 tension, which is, on the contrary, weakened. The employment of 

 this method does not in any way injure the efficiency of that pro- 

 posed by me, and they may both be employed together, where such 

 a course is found advisable. 



To furnish an idea of the increase of effect which I have obtained 

 in my experiments, I will give the following observation. A gal- 

 vanometer being placed in the circuit, the electricity produced by 

 the machine was ]mssed into rarefied air, when the beautiful phaeno- 

 ;inena of light recently studied by M. Quet were produced. When 

 *tbe machine acted under ordinary conditions, the needle of the gal- 

 pvanometer indicated a deviation of 8°. When the condenser was 

 employed, the light produced acquired greater splendour, and the 

 deviation of the needle reached 15°, the intensity of the current 

 being consequently nearly doubled. — Comptes Rendus, March 7, 1 853, 

 p. 418. 



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