AERODROME No. 5 (1896). Dr. Langley has two successful aerodromes, No. 5 and No. 6; the former made the flights of May 6 and the latter that of November 28. The Plate gives scale drawings of No. 5. The weight of this, with fuel and water sufficient for the flights described, is about 30 pounds. The weight of the engine and boiler together is about 7 pounds. The power of the engine under full steam is rather more than 1 horsepower. There are two cylinders, each having a diameter of 14 inches. The piston stroke is 2 inches. The two serews are 39 inches from tip to tip, and are made to revolve in opposite directions; the pitch is 11; they are connected to the engines by bevel gears most carefully made; the shafts and gears are so arranged that the synchronous movement of the two screws is secured. The boiler is a coil of copper tubing; the diameter of the coil externally is 3 inches; the diameter of the tubing externally is three-eighths of an inch; the pressure of steam when the aerdrome is in flight varies from 110 to 150 pounds to the square inch. The flame is produced by the alopile, which is a modification of the naphtha "blow torch" used by plumbers; the heat of this flame is about 2,000 F. Four pounds of water are carried at starting, and about 10 ounces of naphtha. In action the boiler evaporates about 1 pound of water per minute. Flights could be greatly lengthened by adding a condenser and using the water over and over again, but, as Dr. Langley says, the time for that will come later. ON SOARING FLIGHT. By E. C. Huffaker. With an introduction by S. P. LANGLEY. INTRODUCTION. It is generally known that birds sustain themselves in the air in two distinct ways: First. By the direct exercise of mechanical power, as in a large class of birds that flap their wings. Although the exact motions and power of the wing have not yet been studied exhaustively, there is nothing in this method of support, considered as a mechanical contrivance, in apparent contradiction to known principles. Second. Another and important class of birds, including the largest, can fly without flapping the wings, and are able to glide over the landscape (sometimes from horizon to horizon), on nearly motionless pinions, in a manner and with an effect which is not easily explained on known mechanical principles, and which is in striking contrast with the labored way of other birds. This manner, which has never yet been completely accounted for, and which is called "soaring flight," forms the special subject of the following article. In this latter case the bird is in some way held up, as though by an invisible hand, upon the thin and yielding air, on which it seems to float almost like a ship, although its specific gravity is nearly a thousand times as great as that of the air, far greater, in proportion, than that of a ship of solid lead or gold would be to water. There is no obvious explanation of this soaring flight, nor has any yet been offered which is not open to some objection. Passing by the childish idea of the support being derived from the lightness of the birds' hollow bones, or quills, we find ourselves restricted to a very few hypotheses indeed. Perhaps the first of these is that the bird is everywhere upborne by invisible ascending currents. Without in any way denying that such currents exist or that the bird may frequently utilize them, it seems almost superfluous to enter upon a refutation of the idea that these are universally present, even if we allow that they can have ascensional force sufficiently to sustain such masses in the air. "What goes up |