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2. Page’s Experiment, 1838. Electric Spark by Induced Current. Pynchon, p. 427. Dr. Page performed an experiment in which the primary coil was but a few feet in length, while the secondary coil was 320 ft. He included, in the primary circuit, only a few cells of battery. The manner in which he first caused rapid interruptions of the circuit of the primary coil was by the use of what may be called a coarse file, Fig. 2, p. ssss1. He discovered that the E. M. F. during the rapid interruption was so much increased over that of the small battery, that an electric spark would pass between the secondary terminals without first bringing them into contact with each other. ssss1. The result of these experiments was not only the generation of a current of high E. M. F. from a generator of low E. M. F., but also a current of great quantity as compared with currents obtained from frictional and influence machines, whose complete history is found in Mascart’s work on Electricity.

3. Fizeau’s Experiment. Spark in Secondary Increased by Condenser in Primary, 1853. Pynchon, p. 456.—He connected the plates of a condenser respectively to the terminals of an automatic circuit breaker in the primary circuit, and noticed that the sparks between the two terminals of the interrupter produced by the self-induced current were greatly diminished, while those of the secondary coil were about double in length. Since that time it has been universally customary to equip induction coils with condensers in like manner.