John Ernst Worrell Keely

John Ernst Worrell Keely (September 3, 1837 – November 18, 1898) was an American fraudster and self-proclaimed inventor from Philadelphia who claimed to have discovered a new motive power which was initially 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. Keely's claims were highly disputed throughout his career and, in the 21st century, are generally considered to be pseudoscientific.

Keely secured substantial investments from many people, including John Jacob Astor IV. 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 fully discuss the principles on which his motor supposedly operated and also repeatedly refused demands to produce a marketable product by claiming that he needed to perfect his inventions. He became embroiled in several lawsuits, and after Keely's death, evidence of his elaborate fraud was discovered.