As this machine is virtually a series wound machine, the magnet coils each consist of a few turns only of forged copper bars, 1½ in. wide by 1 in. thick, forged to fit the magnet cores.
There is no insulation other than mica wedges to keep the bars from touching the core.
The dynamo furnishes a current of about 5,000 amperes, with an E.M.F. of 50 to 60 volts, and three years ago was claimed to be the largest machine, at least as regards quantity of current, in the world.
The current from the dynamos is led by copper bars to an enormous "cut out," calculated to fuse at 8,000 amperes. This is probably one of the largest ever designed, and consists of a framework carrying twelve lead plates, each 3½ in. × 1/16th in. thick. A current indicator is inserted in the circuit consisting of a solenoid of nine turns. The range of this indicator is such that the center circle of 360°=8,000 amperes.
The electrodes consisted of a bundle of nine carbons, each 2½ in. in diameter, attached by casting into a head of cast iron. Each carbon weighs 20 lb, and, when new, is about 48 inches long.
The head of the electrode is screwed to the copper rods or "leads," which can be readily connected with the flexible cable supplying the current.
The electric furnaces are rectangular troughs built of fire brick, their internal dimensions being 60 in. × 20 in. × 36 in. deep. Into each end is built a cast iron tube, through which the carbon electrodes enter the furnace.
The electrodes are so arranged that it is possible by means of screwing to advance or withdraw them from the furnace.
The whole current generated by the great dynamo of the Cowles Company was passed through the furnace.
In the experiments raw materials only were used, for it was evident that it was only by the direct production of phosphorus from the native minerals which contain it, such as the phosphates of lime, magnesia, or alumina that there was any hope of superseding, in point of economy, the existing process of manufacture.