That the screw action being, in full flight, that of a screw propeller whose axis of rotation forms a slight angle with the vertical, the distance of flight per virtual "revolution" of "screw" wing far exceeds the pitch distance of said "screw."
That consequently a bird's flight answers to an iceboat close hauled; the wing force answering to the wind, the wing angle to the sail, the bird's weight to the leeway fulcrum of the ice, and the passage across direction of the wing flop to the fresh moving "inertia" of the wind, both yielding a maximum of force to bird or iceboat.
That the speed of reciprocation of a fly's wing being equivalent to a screw rotation of 9,000 per minute, proves that a screw may be run at this speed without losing efficiency by centrifugal vacuum.
That as the object of wing or screw is to mount upon the inertia of the particles of a mobile fluid, and as the rotation of steamship propellers in water—a fluid of many times the inertia of air—is already in excess of the highest speed heretofore tried in the propellers of moderately successful flying machines, it is plain that the speed employed in water must be many times exceeded in air.
That with a sufficient speed of rotation, the supporting power of the inertia of air must equal that of water.
That as mere speed of rotation of propeller shaft, minus blades, must absorb but a small proportion of power of engine, the addition of blades will not cause more resistance than that actually encountered from inertia of air.
That this must be the measure of load lifted.
That without slip of screw, the actual power expended, will be little in excess of that required to support the machine in water, with a slower rotation of screw.
That in case the same power is expended in water or air, the only difference will lie in the sizes and speed of engines or screws.
That the greater the speed, the less weight of engine, boiler, and screw must be, and the stronger their construction.