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accurate notions - electromotive force, current strength, and resistance. He indicated the connection of these with experiment, and stated his famous law that the electromotive force divided by the resistance is equal to the strength of the current.

It is perhaps worth recalling, that Henry Cavendish, in his secret and solitary researches, made experiments in 1781, the results of which practically anticipated Ohm's considerations; but Cavendish having satisfied himself, did not apparently consider it worth while to take any one else into account.

In Maxwell's "Introduction to the Cavendish Papers," we find it stated that, "One of the most important investigations which Cavendish made was to find, as he expressed it, 'what power of the velocity the resistance is proportional to.'" (See Cavendish Researches, Arts. 574, 575, 629, 686.)

Cavendish means by "resistance" the whole force which resists the current, and by "velocity" the strength of the current through unit of area of the section of the conductor.

By four different series of experiments on the same solution in wide and in narrow tubes, Cavendish found that the resistance (in his sense) varied as the

1.08, 1.03, 0.976, and 1.00

power of the velocity.