Induction coils, Ruhmkorff coils, and transformers, to be described later, are closely related to this. They all create magnetic fields in the same way and are all electro-magnets.
Fig. 64. Transformers
VII
ELECTRIC HEATING
It was Washington's birthday. The schools were to have a holiday and the Science Club was to hold a special, open meeting at which I had been asked to present the subject of electricity in the household. I replied to the programme committee that that was too large a subject, but that I would talk upon electric heating. I warned them, however, that it would be a dry study, and not an entertainment. They replied that the father of his country had been born at a time of the year when the weather was unfavourable to outdoor sports, and that February usually found them acclimated to vigorous study. Neither they nor their friends objected to study if it seemed to have a motive.
I found an audience composed of old and young, men and women, girls and boys. Most of them had left school—many of them because their teachers thought they were incompetent to continue.