What, now, should be the mechanical construction of a successful flying-machine? How should it be built? In what way should the power be applied? I have tried to make clear what seem to me the principles involved, but the best method in which to apply them can only be found by patient and intelligent study and experiment. Many men have been and are now working at the problem, and that it will be eventually solved seems certain. A bird's muscles, while strong, are not as strong as steel, and while his power in proportion to his weight is great, we can exceed it; and let us not admit that we can not equal his intelligence in applying it.
One of our illustrations shows the flying-machine invented by Mr. Henson in England in 1842, and deserves mention as being the first
Fig. 4.—Henson's Aërostat.
of importance designed to fly without the aid of muscular power. The chief feature was the very great expanse of its sustaining planes, which were larger in proportion to the weight than in many birds. The machine advanced with its front edge a little raised, and the air acting upon the lower surface, when the proper speed had been attained, was expected to lift and sustain it. This speed at the start-off was to be got by running down an inclined plane or hill, and the object of the screw-propeller was simply to keep up the motion. It is unnecessary to say that this machine did not work, and yet Henson evidently had a glimmering of what is required. He introduces the inclined plane and propeller, but does not apply them in a practical way. Such a machine, of course, would be completely at the mercy of the winds; and while he might find a convenient hill to roll down in order to get the required velocity, in coming to earth again there might be trouble,
Landell's flying-machine, invented in 1863, was also provided with an extensive aëro-plane, but differs in having screws acting vertically to sustain the machine in addition to those for driving it forward. Capping all are two parachutes, intended to open and prevent a sudden fall in case of accident. There are four sets of blades on each vertical screw-shaft, on the principle, one would think, that if one set would be a good thing, four sets would be four times as good. They
