NATURAL PHILOSOPHY. 123 



some experiments with this new machine, desired to augment the 

 tension of the electricity it furnishes. A very decided increase of 

 effect is obtained by employing a stronger battery to put the apparatus 

 in activity, and the electricity developed at the poles acquires a 

 marked increase of tension. But this method has an inconvenience 

 which makes the instrument lose its principal advantage, which con- 

 sists in the regularity and duration of its effects. When in operation 

 very brilliant sparks are produced between the surfaces of the inter- 

 rupter ; yet, notwithstanding these surfaces are of platina, they are 

 soon melted and deformed when the current is made more intense, 

 the vibrations of the interrupter consequently become less constant, 

 and the production of electricity soon ceases to take place with regu- 

 larity. The same inconvenience would doubtless manifest itself, if an 

 attempt was made to give to the apparatus of induction superior 

 dimensions to those adopted by M. Ruhmkorff ; for the force of the 

 sparks, which appear at the points of contact of the interrupter, is es- 

 pecially due to an inducted current, which is also produced in the in- 

 ducting wire itself; and if the dimension of the wires, and the number 

 of spiral windings, be augmented, the current will necessarily become 

 more intense, and the sparks stronger. But a careful study of the pe- 

 culiarities of the apparatus, suggested to M. Fizeau a very different 

 method of increasing the energy of the effects produced. This con- 

 sists in disposing a condenser, formed of two plates of tin, each 

 isolated from the other by a coating of varnish, and to connect each 

 of these plates with each of the extremities of the inducting wire. 

 So that the two electricities may spread themselves upon the two 

 surfaces of tin where they will lose, in a great degree, their tension 

 from the effect of the mutual influence exerted through the isolating 

 coating of varnish. When the condenser presents a sufficient surface, 

 (two or three square feet,) it will be seen that communications are 

 immediately established, the light becomes weaker at the point of 

 interruption, and, at the same time, the machine receives a remarkable 

 increase of energy ; the poles then give much stronger sparks, which 

 strike at distances much greater than they could attain before. The 

 condenser may be placed conveniently in a horizontal position, a little 

 above the electro-magnet, and supported by glass feet. 



APPLICATION OF THE TELEGRAPH AND ELECTRICITY TO MIL- 

 ITARY PURPOSES. 



At a recent grand review at Olmutz, Austria, at which the Em- 

 perors of Russia and Austria were present, a sham fight on a grand 

 scale, the siege of the citadel, including the application of electricity 

 on the most recently approved principles of ignition and combustion, 

 constituted the most important of the manoeuvres which were prac- 

 tised. A Vienna paper describes three omnibus-looking vehicles, 

 which were in the camp, each containing a complete electric appara- 

 tus, with a contrivance for laying an insulated wire along the ground 

 by the mere locomotion of the vehicle, the wire being so protected as 



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