It was on May 6, 1896 (the anniversary of which date is now celebrated as Langley Day), that the success was achieved which all who witnessed it considered decisive of the future of mechanical flight. The whole apparatus--steel frame, miniature steam engine, smoke stack, condensed-air chamber, gasoline tank, wooden propellers, wings--weighed about twenty-four pounds. There was developed a steam pressure of about 115 pounds, and the actual power was nearly one horse-power. At a given signal the aeroplane was released from the overhead launching apparatus on the upper deck of the house-boat. It rose steadily to an ultimate height of from seventy to a hundred feet. It circled (owing to the guys of one wing being loose) to the right, completing two circles and beginning a third as it advanced; so that the whole course had the form of a spiral. At the end of one minute and twenty seconds the propellers began to slow down owing to the exhaustion of fuel. The aeroplane descended slowly and gracefully, appearing to settle on the water. It seemed to Alexander Graham Bell that no one could witness this interesting spectacle, of a flying machine in perfect equilibrium, without being convinced that the possibility of aerial flight by mechanical means had been demonstrated. On the very day of the test he wrote to the Académie des Sciences that there had never before been constructed, so far as he knew, a heavier-than-air flying machine, or aerodrome, which could by its own power maintain itself in the air for more than a few seconds. Langley felt that he had now completed the work in this field which properly belonged to him as a scientist--"the demonstration of the practicability of mechanical flight"--and that the public might look to others for its development and commercial exploitation. Like Franklin and Davy he declined to take out patents, or in any way to make money from scientific discovery; and like Henry, the first Secretary of the Smithsonian Institution (to whom the early development of electro-magnetic machines was due), he preferred to be known as a scientist rather than as an inventor. Nevertheless, Langley's desire to construct a large, man-carrying aeroplane ultimately became irresistible. Just before the outbreak of the Spanish War in 1898 he felt that such a machine might be of service to his country in the event of hostilities that seemed to him imminent. The attention of President McKinley was called to the matter, and a joint commission of Army and Navy officers was appointed to make investigation of the results of Professor Langley's experiments in aerial navigation. A favorable report having been made by that body, the Board of Ordnance and Fortification recommended a grant of fifty thousand dollars to defray the expenses of further research. Langley was requested to undertake the construction of a machine which might lead to the development of an engine of war, and in December, 1898, he formally agreed to go on with the work.