We find in Meritens’ English patent, No. 5257, of the year 1878, the series connection of primary coils in the dynamo-circuit also described.
Meritens intended to employ, in place of the many separately insulated circuits of the alternating dynamos of that time, only a single circuit, fed from one large or several smaller dynamos. A large number of induction coils connected in series, were to have been distributed in the different districts of a city. Besides this, Meritens made a combination of the secondary coils, so that he was in a position to produce currents and potentials of various dimensions.
We now come to an inventor, who, in his time, exercised a great influence upon electric lighting by means of transformers, and whose system was in every way a great advance on those of his foregoers. This man was named Jim Billings Fuller. He began to study electric lighting in his laboratory at Brooklyn in the year 1874, giving his whole energy for this object. Fuller’s system of current distribution was first patented in America in the year 1878. The patent No. is 210,317, of 26th November, 1878. His apparatus is represented in Fig. 14. It consisted of an induction coil on which an electric lamp was mounted, to all appearances a Jablochkoff candle. The induction coil, to which we shall return later on, was built in the form of two horseshoe magnets joined together, and having consequent poles at the small coils in the middle, after the manner of the magnets of a Gramme machine. The four large coils are the primary or exciting, the four small coils on the poles of the double magnets are the secondary coils.
The lever MN was of iron, and served to weaken the effects of induction, inasmuch as it formed a magnetic short circuit. Here we find for the first time the employment of a regulating device. Fig. 15 illustrates the method of connection.[1] As already mentioned, Fuller succeeded in setting aside many of the defects which were adhered to in the many very badly constructed transformers of his predecessors. While he was busy carrying his invention into practice, he became a sacrifice to his over-great activity, and on the 15th February, 1879, he was taken away by illness. Only a few hours before his death, he called his foreman to himself, and explained to him the principles of his system. After ending his explanations, he asked him if he had understood all that he had said, and, on receiving an answer from him that he had, he smiled contentedly, and a few moments later he ended a useful life, which had given so much promise of good results.