"More than twenty years ago, Keely, by seeming chance, discovered the unknown polar flow, and without giving any attention to research, on the line of its origin or of its operation, began to construct engines to apply the energy to mechanics. It was not until he had invented his marvelous researching instruments that his true work of evolution began in 1888, which, completed in 1893, has now borne the test of demonstration and given him command of a vibratory circuit for running machinery, both for terrestrial use and for aerial navigation.""The Propeller Described," New Science Review, Vol. 1, 1895, pg. 46. Keely's "propellor" is similar to the present day ion drive systems yet very different. It was all acoustic. He claimed this propellor would propel his airship at 300 mph - and this is in 1890! There are many rumors and suggested news articles claiming he actually did it. 8.5" X 11"