If the experiments be continued under more painstaking technical direction, longer flights can easily be accomplished. Mr. Manly, who designed the Langley engine and screws and who directed the construction and tests of the large aeroplane up to December 8, 1903, reports that he obtained from the propulsion plant a static thrust of 450 pounds, and that he once ran the engine under full load for 10 hours consecutively. This thrust is nearly 100 pounds more than that commonly obtained at Hammondsport with the same plant, and 20 pounds more than the static thrust obtained with the Curtiss motor on the day when it flew the aeroplane with 1,520 pounds aggregate weight. Hence, by restoring the engine and propellers to their original normal working condition they should be able to drive the aeroplane in successful flight with an aggregate weight of nearly 1,600 pounds, even when hampered with the floats and their sustaining truss work. With a thrust of 450 pounds, the Langley aeroplane, without floats, restored to its original condition and provided with stronger bearings, should be able to carry a man and sufficient supplies for a voyage lasting practically the whole day. Dr. Langley's aerotechnic work may be briefly summarized as follows: 1. His aerodynamic experiments, some published and some as yet unpublished, were complete enough to form a basis for practical pioneer aviation. 2. He built and launched, in 1896, the first steam model aeroplane capable of prolonged free flight, and possessing good inherent stability. 3. He built the first internal-combustion motor suitable for a practical man-carrying aeroplane. 4. He developed and successfully launched the first gasoline model aeroplane capable of sustained free flight. 5. He developed and built the first man-carrying aeroplane capable of sustained free flight. [Illustration] * * * * * * Transcriber's note: This e-text follows the text of the original publication. Some minor punctuation inconsistencies have been regularised. Small-capitals in the original publication have been changed to CAPITALS.