John Ernst Worrell Keely (September 3, 1837 – November 18, 1898) was a fraudulent American inventor from Philadelphia who claimed to have discovered a new motive power which was originally described as "vaporic" or "etheric" force, and later as an unnamed force based on "vibratory sympathy", by which he produced "interatomic ether" from water and air. Despite numerous requests from the stockholders of the Keely Motor Company, which had been established to produce a practicable motor based on his work, he consistently refused to reveal to them the principles on which his motor operated, and also repeatedly refused demands to produce a marketable product by claiming that he needed to perform more experiments.