Caption:

French aeronautical theorist, Meusnier (1754-1793) was the first to propose that a navigable balloon should be cylindrical, thus imitating water-borne vessels which had a definite bow and stern. The Robert Brothers were the first to construct such a balloon, under the direction of Louis Philippe, Duke of Chartres. The finished balloon was 52 feet long and 32 feet in diameter with a capacity of 28,274 cubic feet. The means of propulsion consisted of four or five revolving oars which were operated by the aeronauts. On 15 July 1784, the brothers, accompanied by the Duke, ascended from St Cloud in Paris in their creation. However, the experiment was not a great success as the oars provided little directorial control, and it was not until a century later that the airship was developed.