SUMMARY. 



1()7 



The most important general inference from these experiments, as a whole, 

 is that, so far as the mere power to sustain heavy bodies in the air by mechanical 

 flight goes, such mechanical flight is possible with engines toe now possess, since 

 effective steam-engines have lately been built weighing less than 10 pounds to 

 one horse-power, and the experiments show that if we multiply the small planes 

 which have been actually used, or assume a larger plane to have approximately 

 the properties of similar small ones, one horse-power rightly applied, can sustain 

 over 200 pounds in the air at a horizontal velocity of over 20 meters per second 

 (about 45 miles an hour), and still more at still higher velocities. These numer- 

 ical values are contained in the following table, repeated from p. 6(3. It is scarcely 

 necessary to observe that the planes have been designedly loaded, till they weighed 

 500 grammes each, and that such a system, if used for actual flight, need weigh 

 but a small fraction of this amount, leaving the rest of the sustainable weight 

 indicated, disposable for engines and other purposes. I have found in experiment 

 that surfaces approximately plane and of tV this weight are sufficiently strong for 

 all necessary purposes of support. 



Data for soaring of 30 x £.8 inch planes; weight, 500 grammes. 



I am not prepared to say that the relations of power, area, weight, and 

 speed, here experimentally established for planes of small area, will hold for 

 indefinitely large ones ; but from all the circumstances of experiment, I can 

 entertain no doubt that they do so hold far enough to afford assurance that we 

 can transport, (with fuel for a considerable journey and at speeds high enough to 

 make us independent of ordinary winds,) weights many times greater than that 

 of a man. 



In this mode of supporting a body in the air, its specific gravity, instead of 

 being as heretofore a matter of primary importance, is a matter of indifference, 

 the support being derived essentially from the inertia and elasticity of the air on 

 which the body is made to rapidly run. The most important and it is believed 



