beyond the generation of the force, the production of a 30 lb. vacuum and the discharge of a gun. When once his giant mind had grasped the knowledge, which again by seeming chance was imparted to him, he made colossal strides across that unknown tract, the boundaries of which others are now but beginning to explore. Colonel Le Mat was no false prophet, Le Figaro was no untrustworthy herald, when the announcement was made by this French inventor to Monsieur Chevreul, and by this French journal to the public on the 1st day of September, 1888, that the chain which holds the aerial ship to the earth would be broken asunder by Keely's discovery. The nineteenth century holds in its strong arms the pledge, that sooner or later the aerial navy, so long waited for, will traverse the trackless high roads of space from Continent to Continent. It has been supposed by many, Dr. Franz Hartmann among the number, that it requires Keely himself, or another person constituted like him, to set his machinery in motion. Therefore, it has been reasoned that the commercial success of an engine is only possible in case Keely is himself the engineer; or if another man possessing the same seemingly abnormal power could be the engineer. For this reason, says Dr. Hartmann, it is impossible for Keely to instruct any one in his method, so as to enable that one to do what he does. There has been ground in the past for such a statement, it is true, but not now. Keely asserts that when his system is completed, the knowledge of all that is needed for its commercial employment will be more easily acquired than is the necessary skill demanded to enable one to safely operate a steam-engine. When Dr. Hartmann's opinion was made known to Keely, he replied, "Dr. Hartmann's whole conception, in regard to other men being unable to control the operations of my inventions on the sympathetic attractive system, is as incorrect as would be the same conception in reference to operating an electric battery by anyone but its inventor."