20 NOTES ON FLYING-MACHINES. 



horizontally 163 "7 feet when supported by trochoided surfaces, 

 having a total area of 1265 square inches. The foot-pounds of 

 energy represent the actual power stored in the stretched elastic 

 bands and not the thrust of the wings, the two powers are related 

 to one another as the pounds of coal burnt in the furnace of a 

 marine boiler are to the thrust of the screw. The flight of A has 

 a fall of 8 feet, B has a slight rise, and C flies to all intents 

 and purposes horizontally ; a recomputation of the foot-pounds 

 of energy stored in A reduces them from 168*8 as previously 

 stated to 155*7. Thus, it is obvious, the formula for proportioning 

 machines of any other power is nearly as far off as ever, but the 

 evolution of C from those crude efforts, exhibited here previously, 

 has clearly foreshadowed the principle and essential features of 

 one form of the flying-machine of the future ; it is hoped to give 

 these shadowy outlines a tangible form by communicating them 

 through your Journal to the public, so that it will be possible for 

 any practical man if disposed, to make a machine on a large 

 scale with the certainty of some success, without waiting for 

 the completion of a series of experiments that may easily occupy 

 a lifetime when conducted single handed. 



It is interesting to point out how far this trochoidal action of 

 the wing bears out the views of JBorelli, Marey, and Pettigrew. 

 Borelli attributes flight to the elevation and depression of the wing 

 in one plane, and says the pressure of the air on the feathers bends 

 the plane of the wing sufficiently to produce thrust enough for 

 flight ; the interposition of the crank and connecting-rod does 

 this wholly mechanically, if the plane has an equal pressure before 

 and behind the midrib ; if the pressure on the after part of the 

 trochoided plane exceeds that on the forward part, the variations 

 in the angle of the plane are produced, partly by the torsion of the 

 midrib, and partly by the crank and connecting-rod. 



Marey adopts Borelli's idea with regard to insect flight, but by 

 experimenting on a living flying bird, arrives at a close approxi- 

 mation to the plane trochoided conically, (Figs. 6 and 7 Trochoided 

 Plane see page 263 of the third edition of his work on " Animal 

 Mechanism," the distortion of the figure seems attributable to the 

 cramped position and forced action of the bird.) This is peculiarly 

 significant as a similar result is arrived at by an anatomist and 

 by a mechanic. 



Both Marey and Pettigrew observe the figure of eight in insect 

 flight, or rather in the wing flapping whilst the body is stationary, 

 and reproduce it by the torsion and bending of the midrib ; the 

 trochoided plane develops the same figure if the wing socket is 

 imperfectly fitted or the midrib too thin. 



It is frequently asked how such flying-machines are to be 

 steered : this is like asking a skate-maker why he does not fit 



