ELECTKO-MOTIVE POWER. 



simple and effective, are provided, by which the current can he 

 turned on any particular machine, or directed into any room in 

 which it may he required. 



The pile used for heavier work, is a modification of Bunsen's 

 charcoal battery, in which dilute sulphuric acid is used in the 

 porous porcelain cell containing the charcoal, as well as in the cell 

 containing the zinc. By this expedient the noxious fumes of the 

 nitric acid are remove^ and although the strength of the battery 

 is diminished, sufficient power remains for the purposes to which 

 it is applied. 



8. The forms of electro-motive machines constructed by M. 

 Eroment are very various. In some the magnet is fixed, and the 

 armature moveable ; in some both are moveable. 



In some there is a single magnet and a single armature. The 

 power is in this case intermittent, like that of a single-acting 

 steam-engine, or that of the foot in working the treddle of a lathe, 

 and the continuance of the action is maintained in the same manner 

 by the inertia of a fly-wheel. 



In other cases two electro-magnets and two armatures are com- 

 bined, and the current is so regulated, that it is established on 

 each during the intervals of its suspension on the other. This 

 machine is analogous in its operation to the double-acting steam- 

 engine, the operation of the power being continuous. The force 

 of these machines may be augmented indefinitely, by combining 

 the action of two or more pairs of magnets. 



Another variety of the application of this moving principle, 

 presents an analogy to the rotatory steam-engine. Electro- 

 magnets are fixed at equal distances round a wheel, to the 

 circumference of which the armatures are attached at corre- 

 sponding intervals. In this case the intervals of action and 

 intermission of the currents are so regulated, that the magnets 

 attract the armatures obliquely as the latter approach them, the 

 current, and consequently the attraction, being suspended the 

 moment contact takes place. The effect of this is, that all the 

 magnets exercise forces which tend to turn the wheel on which 

 the armatures are fixed constantly in the same direction, and the 

 force with which it is turned is equal to the sum of the forces of 

 all the electro-magnets which act simultaneously. 



This rotatory electro-motive machine is infinitely varied, not 

 only in its magnitude and proportions, but in its form. Thus in 

 some the axle is horizontal, and the wheel revolves in a vertical 

 plane ; in others the axle is vertical, and the wheel revolves in a 

 horizontal plane. In some the electro-magnets are fixed, and the 

 armatures moveable with the wheel ; in others both are moveable. 

 In some the axle of the wheel which carries the armatures is itself 

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