Turning now to the machine and engine, the Military Trials held in 1912, when the Royal Flying Corps was started, represented the first organized effort to assist the evolution of service aeroplanes in this country and a brief comparison will be useful to show the performance of the average machines and engines of that date, at the beginning, and at the end of the war, and of civil machines of to-day. At the Military Competitions of 1912, of the eight types--Avro, B.E., Bristol, Cody, Bleriot, Deperdussin, Hanriot, and M. Farman--the first four were British, though only the Avro had a British engine, and the last four French, fitted with French engines. The average horse-power was about 83, the average maximum speed 67, and the minimum 50 miles per hour; the climb to 1,000 feet was effected in 4-1/2 minutes with an average load of 640 lb., which included pilot, fuel for four hours and useful load. The loading per square foot was, for biplanes, about 4-1/2, and, for monoplanes, 6 lb. On the outbreak of war, and until the end of 1914, of the ten types in use--Avro, B.E., Bristol, Sopwith, Vickers, M. Farman, H. Farman, Caudron, Morane, and Voisin--five were British and five were French and all were fitted with French engines. The average horse-power was still about 83, but the average maximum speed had risen to 74, and the minimum had fallen to 41 miles per hour. The load averaged 609 lb. A remarkable advance in machine and engine construction is shown by referring to the tables for 1918. At the Armistice of the twelve types--Avro, Bristol Fighter, Sopwith Snipe, S.E. 5a, de Havilland 4 and 9a, Vickers Vimy, Handley Page O/400 and V/1,500, Fairey Seaplane 3c, F. 2 A. and F. 5--all were British and, except the de Havilland 9a, which had an American engine, were fitted with engines of British manufacture. The F. 2 A., and F. 5, were twin-engined, while one, the Handley Page V/1,500, was equipped with four engines. The average horse-power was per engine, 344, and per machine, 516; the average maximum speed 111, and the minimum 53-1/2 miles per hour, the climb to 6,500 feet was carried out in 13 minutes and to 10,000 feet in 24 minutes with an average load, including fuel for 5-1/2 hours, of 2,742 lb. The average ceiling was 15,500 feet; the loading per square foot about 8 lb.