It was only after long trials in other directions that Mr. Langley introduced the aeolipile device, which for the first time provided sufficient heat. Even in the aeolipile, however, is was apparent that nothing short of the most complete combustion accompanied by the highest possible temperature of the flame would be sufficient for the extreme demand. To secure this result under all conditions of wind and weather, with the aerodrome at rest and in motion, required the long series of experiments that are given in another chapter. In respect to the generation of heat, then, it is probable that it would be difficult to exceed the performance of the final type of burner in practical work, but in the utilization of this heat in the boiler, as well as in the utilization of the steam there generated, the waste was so great as to be prohibitive under ordinary conditions. But this was not ordinary work, and the simplest protection against radiation from boiler, separator, and engine could not well be used. The framework of the aerodrome is made of thin steel tubes, the main or midrod extending the whole length of the machine and carrying the attachments to which the wings are fastened. Suspended from this midrod by rigid connections is a skeleton hull of steel tubing, shaped somewhat like the framework of a boat, from which, directly abeam of the engines, arms are run out like the outriggers of a rowboat for carrying the propellers. Within this central hull are placed the aeolipile, the boiler, and the engine, which with their auxiliary parts, the pump and the separator, constitute the entire power-generating apparatus. The aeolipile consists of four essential parts: the spherical air chamber containing the supply of compressed air by which the gasoline in the reservoir tank is forced into the burner; the reservoir tank containing the gasoline that is to be used as a fuel; the gas generator wherein the liquid gasoline is heated and converted into gas; and the burners where it is finally utilized to heat the boilers. The air chamber ‹D›, Plate 25, is a spherical vessel 120 mm. in diameter, located at the extreme front end of the hull. It is made of copper 0.25 mm. thick and has two openings. The front opening has a copper pipe 1 cm. outside diameter, to which the air pump for charging the chamber is connected. From the back a copper pipe 5 mm. outside diameter extends to the top of the gasoline reservoir. [Illustration: PL. 25 SIDEVIEW OF STEEL FRAME OF AERODROME NO. 5 SUSPENDED FROM LAUNCHING-CAR, OCTOBER 24, 1896]