received, has been made for the purpose of throwing the hurried account of our agent, Mr. Forsyth, into a connected and intelligible form. “THE BALLOON. “Two very decided failures, of late—those of Mr. Henson and Sir George Cayley—had much weakened the public interest in the subject of aerial navigation. Mr. Henson’s scheme (which at first was considered very feasible even by men of science,) was founded upon the principle of an inclined plane, started from an eminence by an extrinsic force, applied and continued by the revolution of impinging vanes, in form and number resembling the vanes of a windmill. But, in all the experiments made with models at the Adelaide Gallery, it was found that the operation of these fans not only did not propel the machine, but actually impeded its flight. The only propelling force it ever exhibited, was the mere _impetus_ acquired from the descent of the inclined plane; and this _impetus_ carried the machine farther when the vanes were at rest, than when they were in motion—a fact which sufficiently demonstrates their inutility; and in the absence of the propelling, which was also the _sustaining_ power, the whole fabric would necessarily descend. This consideration led Sir George Cayley to think only of adapting a propeller to some machine having of itself an independent power of support—in a word, to a balloon; the idea, however, being novel, or original, with Sir George, only so far as regards the mode of its application to practice. He exhibited a model of his invention at the Polytechnic Institution. The propelling principle, or power, was here, also, applied to interrupted surfaces, or vanes, put in revolution. These vanes were four in number, but were found entirely ineffectual in moving the balloon, or in aiding its ascending power. The whole project was thus a complete failure. “It was at this juncture that Mr. Monck Mason (whose voyage from Dover to Weilburg in the balloon, “Nassau,” occasioned so much excitement in 1837,) conceived the idea of employing the principle of the Archimedean screw for the purpose of propulsion through the air—rightly attributing the failure of Mr. Henson’s scheme, and of Sir George Cayley’s, to the interruption of surface in the independent vanes. He made the first public experiment at Willis’s Rooms, but afterward removed his model to the Adelaide Gallery.