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8a. Feddersen, who used a Leyden jar, modified the experiment by having high resistances in the circuit through which the charge was effected. The duration of the spark was found to be increased. In one experiment, he employed a slender column of water as the resistance, 9 mm. in length. The spark endured .0014 second. With a tube of water 180 mm. the duration was .0183 second. He noticed also that the duration increases directly with the striking distance and with the electrical dimensions of the electrical generator. By varying the resistance of the circuit, he found as it became less, the discharge was intermittent, when further reduced, continuous, (difficult to obtain) ssss1 and when very small, oscillatory—i.e., alternately in opposite directions.

9. Faraday’s Experiment. Brush discharge sound. Phil. Trans. Jan. 1837. Se. XII.—The brush discharge was caused to occur, in his experiments, generally from a small ball about .7 of an inch in diameter, at the end of a long brass rod, acting as the anode. With smaller balls he noticed that the pitch of the sound produced was so much higher as to produce a distinct musical note, and he suggested that the note could be employed as a means of counting the number of intermissions per second. See Mayer’s book on “Sound” § 77, on measuring number of vibrations in a musical note.