After much delay, due to various causes, the quarter-size model, as shown in plan, end elevation, side elevation and three-quarter elevation in Plates 71 and 72, respectively, was taken down the river in June, 1901, in order to make some tests with it from the small house-boat, which had been previously moved to the middle of the river opposite Widewater, Va. A test of it in free flight was made on June 18, its condition at this time being shown by Data Sheet No. 12 in Appendix. The launching apparatus worked perfectly and the aerodrome started off on an absolutely even keel, dropping only a few inches immediately upon leaving the launching apparatus, and continuing straight ahead directly into the light wind of something less than 2 miles an hour. After it had gone only about 100 feet, however, it began to descend slowly, but still maintained a perfectly even balance, and finally touched the water about 150 feet from the house-boat, having been in the air between 4 and 5 seconds. It was immediately recovered, and as soon as the wings could be dried out another test was made, as it was thought probable that the wind had interfered with the carburetor to such an extent that the engine had not received the proper mixture of gas. Upon this second test the launching apparatus again worked perfectly and the aerodrome again flew straight ahead on a perfectly even keel, and at a uniform height from the water until it had gone about 300 feet, when it again began to descend slowly and finally touched the water about 350 feet from the house-boat, having been in the air about 10 seconds. While the tests were very disappointing, owing to the extreme brevity of the flights, yet they showed conclusively that the balancing of the aerodrome was correct, at least as far as motion in a straight line and in a quiet atmosphere was concerned. As one and a half horse-power, which was felt to be the very minimum which would successfully propel the aerodrome, was furnished by the engine only when working at its very best, and as the change in conditions from a quiet state to a velocity of something like 40 feet per second evidently caused a considerable drop in the power because of the change in the gaseous mixture which the carburetor furnished to the engine, it was decided not to make any further test of the aerodrome until the engine cylinders could be reconstructed so as to provide more effective means for cooling it, and thereby a reasonable margin of power above that actually necessary. The aerodrome was accordingly returned to Washington for the purpose of making new cylinders for the engine. In constructing these new cylinders the old cylinder heads from the previous cylinders were used in order to expedite their completion. This proved in the end to be a very great mistake, though at the time it seemed probable that the use of them would save much delay and considerable expense. The new cylinders were