Electromagnetic Induction Machines, 449 



others. Moreover Faraday himself, while on the threshold of 

 my discovery, distinctly negatived its possibility. Reasoning on 

 the magnet as a source of electricity, in a paper " On the Physical 

 Character of the Lines of Magnetic Force" (Phil. Mag. S. 4. 

 vol. iii. p. 415), he says, "Its analogy with the helix is won- 

 derful; nevertheless there is as yet a striking experimental di- 

 stinction between them ; for whereas an unchangeable magnet 

 can never raise up a piece of soft iron to a state more than equal 

 to its own, as measured by the moving wire, a helix carrying a 

 current can develope in an iron core magnetic lines of force of a 

 hundred or more times as much power as that possessed by itself 

 when measured by the same means. In every point of view, 

 therefore, the magnet deserves the utmost exertions of the phi- 

 losopher for the development of its nature, both as a magnet 

 and also as a source of electricity, that we may become acquainted 

 with the great law under which the apparent anomaly may dis- 

 appear, and by which all these various phenomena presented to 

 us shall become one." Now it was the precise and absolute 

 manner in which Faraday stated the definiteness of the relation 

 between the magnetism of a permanent magnet and that of a 

 piece of iron magnetized by its influence, that led me to enun- 

 ciate, in terms equally absolute and precise, the antithesis of 

 his proposition. The anomalous difference between the mag- 

 netic properties of a helix and an iron core to which Faraday 

 directed attention is explained by the property possessed by 

 an iron core, when surrounded with a helix of great length, 

 of acquiring and retaining for a sensible time the magnetic 

 charge in a manner analogous to that by which the Ley den jar 

 acquires a charge of electricity — the acquisition of the charge 

 in the former, as in the latter, being the more rapid as the 

 power of the electromotor is increased. How far Faraday's 

 hopes and preconceptions of the electromagnet as a source of 

 electricity have been realized the results described in this and 

 my former papers will show. Already has it superseded the 

 use of the voltaic battery in every electro-depositing establish- 

 ment of note in this country, and it is making rapid progress 

 abroad. 



That the transformation of mechanical energy into other 

 modes of force on so large a scale and by means so simple will 

 find new and much more important applications than that above 



gressive from those previously obtained by Nollet, Berlioz, and Holmes ; 

 and it is only by the adoption of the principle of electrodynamics accumu- 

 lation {i. e. the exciting of a major electromagnetic induction machine by 

 a minor one fixed on the same base), in accordance with the principles laid 

 down in my former papers, that the results obtained by M. Gramme exceed 

 those from ordinary magneto-electric machines. 



Phil. Mag. S. 4. Vol. 45. No. 30.2. June 1873. 2 G 



