In the war the small aeroplane of the monoplane or biplane type with a small wing spread and equipped with a rotary motor, whose nine or more cylinders revolved with the propeller, or a small V-type motor, was called a scout. These biplanes seldom had a wing spread of over 28 feet and the horse-power of the rotary motors seldom developed more than 150 horse-power, whereas the stationary motors for these same machines generated as much as 300 horse-power, as in the case of the Hispano-Suiza. These machines were used for fighting because they made as high as 150 miles an hour and responded so easily to the slightest movement of the “joy stick” and, consequently, manœuvred so readily. Since trick flying was absolutely essential to air duels these machines were best for this purpose and for quickly getting information of troop movements. The next larger size, seating two men and driven by the same types of motors or even larger twelve-cylinder Rolls-Royce or Liberty motors, but with a wing spread of from 34 to 48 feet, was used for taking photographs, directing artillery-fire, and general reconnaissance in war. The multimotored machines, with a wing spread of anywhere from 48 to 150 feet, were used for bombing at night or during the day. Owing to the size of these machines and because of their slow-flying speed they were easy to land. Some of the scouts weighed, with petrol and two hours’ fuel, less than 1,000 pounds, whereas the four-motored bombers, with 127-foot wing spread, weighed over six tons and could carry a useful load of three tons. The hydroaeroplane does not differ fundamentally from the aeroplane as regards flying principles. In structure it may be a biplane or triplane, but owing to the supports necessary to carry the pontoons it cannot be easily attached to a monoplane. Structurally, it differs from the aeroplane only in having pontoons or a boat substituted for wheels and landing chassis. Owing to the surfaces presented by the pontoons or the hull of the boat, looping is practically eliminated and the spread of these flying craft is much slower than land machines. Although M. Fabre conducted experiments with aeroplanes carrying floats instead of wheels, Mr. Glenn H. Curtiss was the first to successfully construct and fly a hydroplane. At the time of his flight down the Hudson River from Albany to New York he equipped his plane with a light boat to protect himself in case of a forced landing on the water. Encouraged by this experiment under the Alexander Graham Bell Aerial Experiment Association, and by later attaching a canoe, he succeeded in landing and getting off the water. Later he built a hydroaeroplane and flew successfully at San Diego, Cal., thus establishing America as the land which invented and developed the seaplane and flying-boat.