The first who came forward with an industrial employment of the series system were Gaulard and Gibbs, who, in the year 1883, placed before the public an installation of electric lighting in the Royal Aquarium in London.
Fig. 18.
There were two such apparatus as shown in Fig. 18, which were connected in series, and excited with 13 ampères from a Siemens’ alternating current dynamo. The apparatus had the following construction:—The induction coils, a section of one of which is shown in Fig. 19, had three layers of primary wire, and the secondary was wound in four divisions, the ends of the wires of the divisions being led to a commutator. Fig. 20 shows this commutator placed in the middle of four induction coils. The ends of the secondary wires were connected to eight terminals on the upper plate of the apparatus, from which the current could be led away from each pair, or combined at will. By aid of the commutator, the number of coils in circuit could be altered as desired. On the lower plate there was a second commutator, which served the same purpose for the primary circuit.
Fig. 19.
The core of the apparatus consisted of bars of insulated iron, and by means of a rack could be raised or lowered in the coils for the regulation of the current. Both of these arrangements had been already long known.
In the same year another installation for the lighting of some stations on the Metropolitan Railway was taken in hand and carried out.