17
increasing or subsiding, according to the position of the loop with relation to the ends of the magnet. As the current is generated, it flows toward the pieces of metal arranged on the end of the shaft, and from them into what are called brushes, which are flat pieces of metal that rest against those arranged on the end of the shaft so as to have intimate contact with them without retarding their rotation.
This arrangement is clearly shown in the cut. Fig. 4, in which a is a shaft, to which is fixed a drum or core b, wound with a number of coils of insulated wire c; that is, wire which is carefully covered with a material which practically prevents the passage of electricity through it. These wires are connected together at the front end of the drum, and are also secured to curved pieces of metal d, which for the sake of clearness, are shown with that end of the shaft removed, and as also having the brushes e e resting against them.
These plates, d d, vary in number
