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April 1913   FLY MAGAZINE   17

had previously been built, but no one had flown save a few— Chanute in this country, and Lilienthal and Pilcher abroad, who were engaged in experimentation.

    "In this situation the patentees conceived the idea of hinging dihedral planes to supports at their front and rear margins with flexible joints to permit varying or tilting them at their extreme lateral ends by the use of suitable levers to impart to the aeroplane surface a helicoidal twist. On this point the specification says:

    "'We prefer this construction and mode of operation for the reason that it gives a gradually increasing angle to the body of each aeroplane from the central longitudinal line thereof outward to the margin, thus giving a continuous surface on each side of the machine, which has a gradually increasing or decreasing angle of incidence from the center of the machine to either side. We wish it to be understood, however, that our invention is not limited to this particular construction, since any construction whereby the angular relations of the lateral margins of the aeroplanes may be varied in opposite directions with respect to the normal planes of said aeroplanes comes within the scope of our invention. 

    "It was believed in the beginning that by warping or depressing the margins of the supporting planes at opposite ends, the aeroplane could be controlled in its movements and its equilibrium maintained in flying, and the proofs show that in their earlier efforts the inventors did not design to use either a horizontal rudder in front of the machine or a vertical rudder at the rear, but later, before the application for patent was filed, these instrumentalities were added. The moveable vertical rudder or tail exerts a retarding influence on the side of the machine which in flying has a tendency to move ahead of the opposite side, and thus assists the wings or marginal ends in keeping the aeroplane properly balanced.

    "To induce a construction of the claims in controversy that will exclude defendants' aeroplanes it is contended that the patentees merely improved the known gliding machine—a contrivance for gliding down slopes—and that the wing tips, horizontal rudder, and vertical rudder were old separately and in combination. In the year 1896, and previously, Lilien-thal had flown experimentally with a gliding machine which was afterwards wrecked. Later, the Pilcher and Cahunte structures, of both the monoplane and biplane type, were used for experimental flying, but they also were failures, and little success was achieved in correcting their imperfections.

    "In a published address by Chanute, who had carefully studied the subject of aerodynamics and disclosed a keen familiarity with flying machines of the aeroplane type, there is contained a precursory review of the aeroplane and its practicability up to the year 1897. In this address he points out the differences between curved and flat planes with re-gard to the effect of air pressure thereon, but his descriptions were not sufficiently definite to suggest the later improve-ments by the patentee's. He declared that the use of a horse-power motor to facilitate flight, if of sufficiently light weight, was a minor detail and not a serious problem, and that the maintenance of the equilibrium was the most important problem in connection with aerial navigation. While his ex-perimentation and publications were helpful to the patentees, it is not contended by the defendants that they were anti-cipatory of the claims in suit, but merely that they showed the progress that had been made in efforts to make possible human flight.
    "A summary of what had gone before in aerial machinery unmistakably discloses, first, publications which did not contain descriptions of apparatus of such clearness and definiteness as to enable the skilled in the art to construct therefrom an operative device, or clearly suggesting ways or means to solve the problem of lateral balance, and, second, exhibit patents, which, as Judge Coxe says, 'emerged from oblivion solely to meet the exigencies of the occasion' and which contain undeveloped plans or ideas for construction incapable of successful operation.

    "As the defendants have not proven that the defects attributed to such devices could have been removed by the exercise of the skill and training of an engineer or mechanic, I am on opinion, after complete consideration of the testimony on both sides, that the patentees by their method of securing the equilibrium of the planes made an important advance in an embryonic art. They were not the first to conceive the idea of using monoplane or biplane surfaces for flying, nor the first to support two planes at their margins one above the other, or to use vertical tails or rudders for steering, or to plane horizontal rudders forward of the machine to guide it upward or downward in its flight. The prior separate use of such elements is freely admitted by the patentees, but they assert, rightly I think, that the patented combination was a new combination performing a new and novel result.

    "The antecedent patents, the efforts to perfect the gliding machine and to provide means for restoring equilibrium; in short, the many unsuccessful attempts to remedy existing imperfections in aerial machinery all bear witness to the fact that the achievement of the patentees required the exercise of the inventive faculty. Having attained success where others failed, they may rightly be considered pioneer inventors in the aeroplane art. Their concept was practical, and their combination of old and new elements meritoriously advanced the operativeness of aeroplanes of this type from which astonishing flights have resulted.

    "Of course, it is not intended to decide, and such decision should not be inferred from what has been stated, that by the adaptation described in the specification and claims in suit the capsizing or upsetting of the aeroplane has been made impossible or its ability in the air positively assured, for this is not contended. But that the invention is a strong factor in restoring equilibrium where, owing to the fluctuations of the wind or to other disturbing causes, the aeroplane is shifted or swerved from its course, the warping device imparting to the aeroplane surface a helicoidal twist, is used, and at the same time the vertical rudder is turned to recover the equilibrium. And even if the patentees were not strictly pioneers in the sense of producing an apparatus novel in its entirety, they nevertheless strikingly surpassed their predecessors in devising means for restoring lateral balance and are entitled to a liberal construction of their claims in controversy that will include an aeroplane appropriating substantially the same instrumentalities and the same principle of operation.
    "The defendants urge that patentees' invention is without practical utility, that the flat planes described in the speci-fication were never used, that the vertical rudder is useful merely to equalize resistance, that the patent fails to disclose the manner of effecting the equalization of the differences of air pressure, and argue that in turning complainant's ma-chine the ailerons are warped with the result that the aero-plane swings or circles toward the side on which the greater angle of incidence was produced, that by such maneuvering to prevent upsetting complainant's machine has to be turned from its course, it being impossible to further turn the vertical rudder, and they argue that defendant's aeroplane is radically different from complainant's. They also claim that it was not until the vertical rudder was constructed to move inde-pendently of the ailerons, as in defendants' aeroplane, that an operative device was produced.
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