122 ANNUAL OF SCIENTIFIC DISCOVERY. 



experiment fail completely, and to destroy, or, at least, place in 

 abeyance the explanation given of it, M. Gaugain only introduce 

 into the tube a few drops of alcohol, which rising in vapor, should in 

 nowise hinder the heat from playing its usual part, but which operates so 

 as to place the two wires in the same chemical positions ; for the flame 

 of the spirit-lamp really forms around the exterior wire an atmos- 

 phere of alcohol. It is consequently very probable that in the already 

 mentioned experiment, the disengagement of electricity was due to 

 an especial chemical action, which cannot be well defined, but whose 

 effect is annulled by opposing to it a similar chemical action. M. 

 Gaugain thinks a gaseous couple, analagous to that discovered by M. 

 Grove, may play a part in the matter. The idea is ingenious, but it 

 does not furnish a complete explanation, for in Grove's battery there 

 is a conducting liquid, while there is nothing analagous in the data 

 of M. BecquerePs experiment. 



RUHMKORFF'S ELECTRICAL APPARATUS. 



It is not the least brilliant of Mr. Faraday's claims to high scientific 

 rank, to be the discoverer of that singular influence exercised on 

 distant points by electrical currents, the influence which he called 

 induction. Before him no one had succeeded in obtaining with the 

 battery, electricity of tension like that furnished by the electrophore 

 and the old fashioned plate electrical machine. The battery does not 

 of itself give the spark which flashes between two points, but the cur- 

 rent it produces can act and influence a neighboring conductor and 

 produce there all the signs of static electricity. The current of induc- 

 tion, (so called to distinguish it from that of the two electricities 

 accumulated in the exterior and interior foil coatings of the Leyden 

 jar) does not manifest itself in a complete circuit, except under the 

 influence of another current subject to variations of intensity. Sup- 

 pose the current of a battery is passed through a metal wire, wound 

 around a hollow bobbin, in whose interior a second wire is wound, just 

 the same as the wire on the outside ; if the communication of the 

 battery with the exterior wire be frequently interrupted, the exterior 

 wire will excite in the inside wire currents of induction, properly so 

 called, and which are generally endowed with a great degree of tension ; 

 the introduction of a bar of soft iron in the centre of the bobbin, 

 increases to a still higher degree the intensity of the phenomena. 

 The inducted current then becomes so powerful, that to prevent the 

 wire discharging itself on itself, it is necessary to separate the different 

 coils by a resinous and insulating substance. To insure the action of 

 the apparatus without the intervention of any person, an interruptor, 

 (according to the method suggested by M. de la Rive) is placed in a 

 proper position, and the magnetized iron suffices to agitate it. Such 

 is the apparatus invented by M. Ruhmkorff ; it is an excellent machine, 

 giving forth brilliant sparks, powerful shocks, and which may be 

 advantageously substituted for the electrical machine, in all experi- 

 ments relative to static electricity. M. Fizeau, when about making 



