Abstract :
The existence of a mechanical force in the direction of the axis of a conductor, the recognition of which the writer has been urging for many years, has been strenuously opposed by many (chiefly teachers and book writers) because it does not fit in with Maxwell´s mathematical system, which recognizes only perpendicular forces. No one, however, has shown that it does not nor cannot exist, and it seems that its acceptance is now gaining, though slowly.
