From John Collins WEB-site:
In 1712 Johann Bessler (aka ORFFYREUS) exhibited a machine which he claimed, drew its energy from gravity. Despite nearly twenty years of the most stringent tests, examinations and public trials, not the slightest sign of deception was ever found. Bessler died 33 years later, in poverty, still maintaining that his machine was genuine and there was no convincing evidence to the contrary.He had a number of supporters as well as enemies, and among his champions were some of the most respected men of the day. These men, included Gottfried Leibniz and Christian Wolff, top scientists of the calibre of Newton.