Page:Popular Science Monthly Volume 3.djvu/604

588 Thus the revolving armature presents two groups of coils, generating two equal but opposite streams of electric force. The wire being unbroken, the currents neutralize each other, and there is no circulation. The result may be likened to what would be produced by taking two batteries, each of 20 cells, and connecting them in opposition by joining similar poles.

The problem now is to pick up these dormant currents and utilize their force. Its solution is apparent from the comparison we have just made. To collect the electric current from two batteries which are connected together in opposition, it is only necessary to fasten conducting wires to the two points of contact of similar poles, when the whole force of the batteries will flow along these wires. They were hitherto opposed, they now flow together, quantity-wise. M. Gramme, in the second portion of his invention, has adopted this artifice in an ingenious manner.



The various sections of the continuous electro-magnet are connected with radial pieces of copper shown at R in Figs. 3, 4, and 7, insulated one from the other, but coming very close. The termination of one coil of wire and the commencement of the adjacent coil are soldered to the same radial connector, of which, therefore, there are as many as there are coils. These radial connectors, on approaching the centre, are bent at right angles, as shown at R, Figs. 4 and 7, and pass through to the other side, where their ends form an inner concentric circle, being still insulated one from the other.

The friction-pieces F (Figs. 4, 5, and 6), consisting of disks of copper, are pressed, by means of springs shown at r (Figs. 5 and 6), against the circle formed by the extremities of the conducting radii R, at two points which are accurately in the equatorial line; that is to say, at