588 Intelligence and Miscellaneotts Articles, 



nevertheless that it would be useful to give greater power to the in- 

 strument, and especially to be able to increase the tension of the 

 electricity furnished by it. 



A very sensible increase of effect is obtained by employing a 

 stronger pile to set the apparatus in action, and the electricity de- 

 veloped at the two poles of the machine acquires thus a very marked 

 increase of tension. But this increase is accompanied by an incon- 

 venience which deprives the instrument of its principal advantage, 

 which consists in the regularity and the duration of its effects. One 

 of the essential parts of the machine is M. de la Rive's vibratory con- 

 tact-breaker. When the instrument is in action, very brilliant sparks 

 are produced between the surfaces of the breaker, and although these 

 surfaces may be formed of platinum, they are soon fused and de- 

 stroyed when the current is rendered more intense ; the vibrations 

 becoming less constant in consequence, the production of electricity 

 soon loses its regularity. 



The same inconvenience would no doubt be produced by giving 

 the machine larger dimensions than those adopted by M. Ruhmkorff, 

 for the force of the sparks which are produced at the point of vibra- 

 tion is due principally to the current induced in the conducting wire 

 itself; and if the dimensions of the wires and the number of turns 

 of the spire be increased, this current would of course become more 

 intense and the sparks stronger. 



But an attentive study of the peculiarities of the apparatus soon 

 led to the discovery of an entirely different and very simple means 

 of increasing the energy of the effects produced. Many experiments, 

 which it would take too long to describe, tend to show that the current 

 of induction which is produced in the inducting wire itself at the 

 moment of the rupture of the circuit, exercises a considerable in- 

 fluence on the production of electricity in the induced wire which 

 terminates the two poles of the machine. When this current is 

 produced freely and takes a great development, the poles give but 

 little electricity ; but when, on the contrary, this current meets with 

 obstacles, and only attains a slight development, the poles give much 

 electricity, and the power of the machine becomes greater. Several 

 arrangements served to prove this fact ; I may mention the employ- 

 ment of metals more fusible than platinum on the surfaces of the 

 breaker, and the union of the vibrating parts by fine wires of differ- 

 ent lengths. This principle being admitted, it follows, that in order 

 to increase the power of the machine, it is sufficient to oppose the 

 development of the current which is produced in the inductor wire 

 at the moment of the rupture of the circuit, and it is easy to see 

 that this result must be obtained by acting upon the tension pos- 

 sessed by this current and rendering it weaker. In fact, when the 

 machine is in action, the great light of the sparks which appear at 

 the point of rupture, indicates that the current in question acquires 

 a great development, and this is the case because the electricity 

 possesses sufficient tension to pass with facility the space which 

 separates the vibrating pieces : if the tension became weaker, the 

 space to be passed presenting a constant resistance, the passage 



