150 ANNUAL OP SCIENTIFIC DISCOVERY. 



powerful effect. We think there is no doubt that if there was no 

 residual magnetism there would be no excitation of electricity, 

 unless the coils of the revolving keeper should happen to be at an 

 angle to the magnetic meridian. But the true reason for the 

 magnetic and electric accumulation is the difference in time re- 

 quired for the maximum excitation of these two forces in given 

 conductors, combined with the known law of their mutual action 

 and re-action. If magnetic induction were as instantaneous as 

 electric induction is, there could be no augmentation of the re- 

 sidual magnetism, or, at most, the amount would be so small that 

 it would be inappreciable, "seeing that action and re-action are 

 always equal and opposite. 



By this arrangement magneto-electric machines may be made, 

 as it were, independent of the magnetic power of permanent ex- 

 citing magnets; an electro-magnet and armature being used 

 instead of a permanent magnet and armature, the electro-magnet 

 having in addition a small permanent magnet as keeper; the 

 machine being set in motion and this permanent magnetic keeper 

 being removed, the residual magnetism combined with mechani- 

 cal motion being sufficient to produce the greatest effects. Of 

 course, in such a machine there is a great expenditure of me- 

 chanical force, and therefore, as an economical mode of exciting 

 the electric force, this arrangement is not likely to be used ; but 

 in cases where enormous amounts of electric force are required, 

 this law of magneto-electric induction shows how it may be pro- 

 duced without limit,, except that of the available driving power. 

 It is not yet decided whether by this means electricity can be 

 produced economically from steam power or not. It is certain 

 that Mr. Wilde's arrangement has not yet produced it economi- 

 cally, and this new arrangement will not produce it more cheaply, 

 as it commences with a smaller amount of magnetism than Mr. 

 Wilde's does, and, in fact, nearly all the magnetism and elec- 

 tricity has to be produced from the mechanical force applied. 

 We have in this acquired an addition to our knowledge of elec- 

 tric and magnetic induction, that, by the dynamic difference of 

 these forces and their mutual action on each other, an indefinite 

 amount of augmentation of each can be produced. Thus, we 

 have progressed one step farther in the most difficult problem in 

 the science of magnetism and electricity, the problem of induc- 

 tion. Mech. Mag. y 1867. 



WILDE'S ELECTRIC MACHINE. 



At a conversazione of the Royal Society, March 2, 1867, Mr. H. 

 Wilde, of Manchester, exhibited his wonderful electro-magnetic 

 machine. There was something imposing in the sight of the ap- 

 paratus itself, with coils 4 feet high and 10 inches thick, contain- 

 ing 1,400 weight of copper wire, and between them an armature 

 made to rotate 1,500 times in a minute by a 15-horse power steam 

 engine standing just outside one of the windows. Round and 

 round flew the wheels, every rotation sending two fresh streams 

 of electricity into the coils, until on a sudden the intense current 



