To England goes the distinction of the first practical attempts to solve the problems of flight; and it is the work of Sir George Cayley, an eminent scientist and engineer, that next merits attention. In a series of articles, published in _Nicholson’s Journal_ during the years 1809-10, he forecasted many of the principles that go to the making of a modern-type aeroplane. He advised the construction of machines with fixed, outstretched wings like those of a bird; but he did more than this, for it is admitted generally he was first to point out that, to increase their lifting power as they were moved through the air, these wings should not be flat, but should be curved from front to back, or arched upward (Fig. 4). How important this suggestion was, subsequent experimenters were to show. Sir George Cayley realised also that a tail-plane, carried at the rear of a machine, would give it equilibrium, and might be moved up and down to control ascent or descent; and he used a rudder upon models, to steer them from side to side. He advised the use of steam engines as a motive power, and of revolving propellers to drive a craft through the air. But, like many another man, he was before his time. He built experimental craft--one, a model glider, which would sail down gracefully from the top of a hill; and another, a far larger machine, which would bear a man through the air, for a distance of several yards, if he ran forward with it against the wind. But the difficulty of obtaining a sufficiently light and practical motor, either of steam or other power, was an obstacle that proved insurmountable. One light engine, which Sir George Cayley planned, was to be driven by a series of gunpowder explosions in a cylinder; but the suggestion came to no practical issue. This scientist did not write or work in vain. He compiled data which was invaluable, and interested and encouraged other men--even those, indeed, who in due course made the conquest. One of the first to work upon Sir George Cayley’s theories was an experimenter named Henson. He planned an ambitious machine weighing about a ton. It was to have planes of canvas stretched over a rigidly trussed frame of bamboo rods and hollow wooden spars; and these planes were to contain 4500 square feet of lifting surface, and be driven by screws operated by a steam engine of 30 h.p. (Fig. 5). But this craft did not take practical shape, although in its appearance and many of its details it bore a resemblance to machines which ultimately were to fly. In the specification of the patent he took out for his invention, Henson indicated that it was for “Improvements in locomotive apparatus and machinery for conveying letters, goods, and passengers from place to place through the air.” [Illustration: FIG. 5.--Henson’s proposed Machine.] Explaining his theories in this same specification he wrote: