=Early Records.=—The earliest reference to pneumatic transmission of which we find any record is a paper presented to the Royal Society of London, by Denis Papin, in the year 1667, entitled “Double Pneumatic Pump.” His plan was to exhaust the air from a long metal tube by two large cylinders. The tube was to contain a piston, to which a carriage was attached by means of a cord. The “American Cyclopædia” goes on to say, “More than a century elapsed before any further effort in this direction was made. Paucbrouke’s ‘Dictionnaire Encyclopédique des Amusements des Sciences’ (1792) gives a description of a machine by M. Van Estin, by means of which a hollow ball holding a small package was propelled by a blast of air through a tube several hundred feet in length, and having many curves. This plan seems, however, to have been more an amusement than an attempt to introduce an industrial scheme. With more regard to practical results, Medhurst, an engineer of London, published a pamphlet on the subject in 1810. He proposed to move small carriages on rails in air-tight tubes or tunnels, by compressed air behind, or by creating a partial vacuum in front. In 1812 he published another pamphlet; but the plan was not put into successful operation, principally from insufficient means of exhaustion. About 1832 he proposed to connect the carriage inside such a tube with a passenger carriage running on the top of the tube; and, although the latter project has never been commercially successful, it was the first to be practically attempted. More than a score of patents were taken out on the Continent and in England and America, none of which met with any practical success. Returning to the original idea of Denis Papin, inventors attempted to accomplish pneumatic transmission by moving the load inside the tube, and in course of time achieved success. In France MM. Jarroux and Taisseau presented a project for atmospheric telegraphy before the Academy of Sciences, and they were succeeded in the same direction by MM. Brochet and Ardor.”