As a result of reading the various communications to the Scientific American and Supplement, and Van Nostrand's Engineering Magazine, including descriptions of proposed and tested machines, and the reports of the British Aeronautical Society, the writer of the following concludes:

That, as precedents for the construction of a successful flying machine, the investigation of some species of birds as a base of the principles of all is correct only in connection with the species and habits of the bird; that the general mechanical principles of flight applicable to the operation of the same unit of wing in all species are alone applicable to the flying machine.

That these principles of operation do not demand the principles of construction of the bird.

That as the wing is in its stroke an arc of a screw propeller's operation, and in its angle a screw propeller blade, its animal operation compels its reciprocation instead of rotation.

That the swifter the wing beat, the more efficient its effect per unit of surface, the greater the load carried, and the swifter the flight.

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.

That, in consequence, solid metal worked down, instead of bolts and truss work, must be used.

That as the bird wing is a screw in action, and acts directly between the inertias of the load and the air, the position and operation of the screw, to the load, must imitate it.

That, in consequence, machines having wing planes, driven against one inertia of air by screws acting in the line, of flight against another inertia of air, lose fifty per cent. of useful effect, besides exposing to a head wind the cross section of the stationary screw wing planes and the rotating screw discs; and supporting the dead weight of the wing planes, and having all the screw slip in the line of flight, and carrying slow and heavy engines.

That as a result of these conclusions, the supporting and propelling power should be expressed in the rotation of screws combining both functions, the position of whose planes of rotation to a fixed horizontal line of direction determines the progress and speed of machine upon other lines.

That the whole weight carried by the screws should be at all times exactly below the center of gravity of the plane of support, whether it be horizontal or inclined.

That while the permanently positioned weight, such as the engines, frame, holding screws, etc., may be rigidly connected to or around the screw plane of support, the variable positioned weight, such as the passenger and the car, should be connected by a flexible joint to the said plane of support.

Consequently, the car may oscillate without altering its weight position under center of supporting plane, thus avoiding an involuntary alteration of speed or direction of flight.

That to steer a machine so constructed, it is merely necessary to move the point of attachment of car to machine proper, out of the center of plane of support in the desired direction, and thus cause the plane of support or rotation of propellers to incline in that direction.

That the reservoir of power, the boiler, etc., should be placed in the car, and steam carried to engines through joint connecting car with machine.

That at present material exists, and power also, of sufficient lightness and strength to admit of a machine construction capable of a limited successful flight in any fair wind and direction.

That such machine once built, the finding of a power for long flights will be easy, if not already close at hand in electricity.

That the easiest design for such actual machine should be adopted, leaving the adaptation of the principles involved to the making of more perfect machines, to a time after the success of the first.

That such design may be a propeller, and its engine at each end of a steel frame tube, supporting tube horizontally, a car to be supported by a universal joint from center of said tube, and the joint apparatus movable along the tube or a short distance transverse to it, to alter position of center of gravity.

That the machine so built might traverse the water as well as air.