upon the nature of vibration, was led into the field of invention; and while experimenting with one of his inventions, he suddenly stepped into that great unknown territory which lies beyond the horizon of ordinary matter. It took him nearly a score of years to find out where he was. Years of experiment followed before he was able to summon the Geni at will; for when his lever first registered a pressure of 2000 lbs., while subjecting water to the action of multiplied vibrations, he had no idea how to proceed, as far as the number of vibrations were concerned, to repeat the operation. Commencing at a certain point, he increased the vibrations day by day until, six years later, he was able to effect the dissociation at will. But at that time Mr. Keely had too much mechanical work to do to give any of his time to theorizing. He was in the clutches of a speculating Keely Motor Company, whose cry was, "Give us an engine!" and day and night this toiler fought his way in the underground labyrinth, thinking only of a commercial engine. It was not until Macvicar's "Sketch of a Philosophy" fell into Mr. Keely's hands that he realized he had imprisoned the ether. This was in 1884, and, four years later, in 1888, Professor Hertz of Bonn announced that we were using the ether, without knowing it, in all electro-magnetic engines. By this time Keely's researches in vibratory physics had led him well on his way in the construction of hypotheses as to "what sort of things molecules are, and in what way they vibrate." An hypothesis treats a supposed thing as an existing thing, for the purpose of proving, by experimental demonstration, whether the supposition is correct or not. At a critical juncture, Mrs. J. F. Hughes (a grand-niece of Charles Darwin), hearing of Keely's researches, became interested in his work; and her book on "The Evolution of Tones and Colours" was sent to Mr. Keely. An expression used by Mrs. Hughes in that work, brought a suggestion to Mr. Keely. The veil of darkness was rent asunder which had enveloped him in what he called "Egyptian blackness," and from that time he worked no longer in the dark.