Opinion of the Court when once aloft they function to maintain equilibrium and lateral control, the vital necessity for which is obvious. If the operator desires to turn in either direction, or the lateral equilibrium of his plane is disturbed, he may accomplish the former and retake the latter by a process of change in the wing surface. Montgomery, securing the front portion of his wings rigidly and unmovable to his structure, so adjusted the rear portion relatively to the front portions as to change the surface of his wings by a change in their curvature. He did, by the application of a control device, make it possible to lower one side of the rear portion of his wings. which at the same time functioned to permit the other side of the rear portion to rise and thereby evolved this principle of wing warping. This was accomplished without changing angularly the wing surface, and the claimed. novelty resides in making the change of curvature integral with the wings themselves, i. e., the wing itself responded to the movement without the introduction of hinged ailerons. The result was a change in the rear cambered sections of the wings and offered to air currents the essential characteristics of an increased lift upon one side of the plane and a decreased lift on the other, enabling the airplane to turn in either direction. Montgomery was not the first to recognize or avail himself of the principle of changing the form of wing surface to attain the desired results. On the contrary, he encountered at the outset of his application for a patent two prior patents embodying the conception and was compelled to limit his claims to avoid the patented structures. Beeson on January 24, 1888, secured a patent for a structure illustrated by the following device: Beeson relied upon a curvel plane, to the rear portion of which he hinged an elongated element functioning upwards and downwards, which manifestly served to angularly vary the surface of his wing. Boswell's patent, illustrated by his Fig. 1, which we reproduce, disclosed a conception of the structure embodied in certain of Montgomery's claims as filed. Boswell's structure also obtained an angular change in wing surface. The Commissioner of Patents rejected the patentee's claims 1, 2, 3, 4, 17, and 24 upon the patents cited above. Montgomery submitted amendments in answer to the rejections, in which he said: "The essential distinction of this aeroplane with respect to its capability of changing surface, is that such change is effected and lies wholly within its own integral borders, by a change in its own curvature, in contradistinction to a general angular change such as results from the relative movement of a sectional attachment like the hinged tail of the reference." Opinion of the Court We need not indulge citation to disclose the legal effect of this proceeding. No. 728,844. TO MODEL. L. A. BOSWELL. PATENTED MAY 26, 1903. STEERING MECHANISM FOR DIRIGIBLE AIR SHIPS. APPLICATION FILED SEPT. 24, 1901. From the Revue de l'Aéronautique, vol. 4, published at Paris in 1893, we cite the following quotation: "It is known that the characteristic of a spiral is to turn about a center from which it is always receding and (fig. 27) that all tangents, at no matter what point of the curve, form similar angles with the radius; it is thus possible to trace spirals of greater or less curvature. Opinion of the Court "This curvature is indispensable to a moving surface to enable it to obtain the maximum support in the air. It is also applicable and indispensable to individual feathers and to the propeller blades. "It may be termed the universal sustentation curve of flight and support in the air. The arching, as regards the degree of curvature of the concavity of the wings, will vary according to the speeds and loads, but without ever losing the character of a spiral. For all wings, without exception, small or large, the central or starting point C of the spiral curve coincides with the front of the wing; the Figures 26 and 27, representing two absolutely similar spirals, afford an example of this. On that of Fig. 26 is seen a full line which shows the shape of a large wing; on Fig. 27 the full line represents another wing, but much smaller. The horizontal lines H indicate the direction of translation. The same wing may change its degree of curvature during flight, but it will be only a modification of the spiral. "II. Laws common to all wings "All wings, of whatever shape and nature they be, must obey the same laws. It can not be otherwise, because the difficulties of locomotion in the atmosphere especially when the latter is disturbed, and the manoeuvres of starting from and landing on the ground will be the same for all aerial machines. Aeroplanes will also inevitably undergo great changes in their weight through the consumption of fuel or by being lightened if they let fall any part of their load to the earth. "From all this arises the necessity of being able to guide or to retard or accelerate the speed of translation. And to be able to attain this end it is necessary that the wings should be capable of making four principal movements during flight: 1. To be moved forwards or backwards in their entirety. "2. To be folded up, so as to diminish or extend their surface. "3. To be warped. "4. To vary at will the curvature of the universal curve. "All the combinations of frameworks, of articulations, of tendons and membranes are made with this end in view. "Because of the great difficulties which accompany the question of speed, we have been obliged to make wings for slow speed and high speed machines." Opinion of the Court Lilienthal in 1895 demonstrates in his Letters Patent #544816 a distinct conception of the value and functioning of curved wings in a flying machine. Lilienthal was a distinguished engineer and scientist; he successfully accomplished thousands of glides, gave to the art publication of his experiments, and is prominently recognized by more than one outstanding scientist as contributing to the art most vital and necessary principles of the way in which air currents may be utilized in flying machines. On May 26, 1906, Orville Wright and Wilbur Wright, of Dayton, Ohio, received their patent #821393. The two Wrights first became interested in aviation in 1896. They were close students of the science, and early in their careers became convinced that equilibrium and control were the vital factors to be obtained if a heavier-than-air machine was ever to materialize. To this end they devised in July, 1899, a method of twisting or warping wing surface. A model was constructed along this line, a model clearly disclosing the conception of shifting one wing surface forward or back relatively to the other, and warping them by the same movement. This model was tested and responded satisfactorily. In 1900 the Wrights constructed a man-carrying model and it was tested at Kitty Hawk, North Carolina, in September and October, 1900. This particular machine, a glider, speaking now of wing surfaces, was so constructed that adjustments connecting the wings by flexible joints with upright posts, enabled the operator, "lying prone in a cradle," to actuate a wing warping effect by the sidewise movement of his body. The machine was flown a number of times with an operator on board during some of the flights, and without one at other times. It is true that the wing warping was accompanied by changing the relative position of the wings in flight, and not in the precise manner the patent in suit at a later point of time disclosed; but the demonstration of the effectiveness of the principle was firmly established. Lateral control and equilibrium were obtained for the first time effectively, leaving open to subsequent inventors the solution of a better method, if possible, to obtain the identical result. The Wrights, so far as the record herein is concerned, were the first to construct a device which suc |