NO. 3 I.\M;i,KY MEMOIR OX MECHANICAL FLIGHT 3 



result, and all the experiments given in this book arc to be considered only as 



approximations to exact truth. All were made with a view, not to sonic remote 

 future, but to an arrival within the compass of a lew years at some result in 

 actual flight that could not be gainsaid or mistaken. 



Although many experimenters have addressed themselves to the problem 

 within the last few years — and these have included men of education and skill 

 —the general failure to arrive at any actual fljghl has seemed, to throw a doubt 

 over the conclusions which 1 had announced as theoretically possible. 



When, therefore, I was able to state that on May 0, 1896, such a degree of 

 success had been attained that an aerodrome, built chiefly of steel, and driven 

 by a steam engine, had indeed flown for over half a mile — that this machine had 

 alighted with safety, and had performed a second flight on the same day, it was 

 felt that an advance had been made, so great as to constitute the long desired 

 experimental demonstration of the possibility of mechanical Might, These results 

 were communicated to the French Academy in the note given below/ 1 



Independently of the preliminary experiments in aerodynamics already pub- 

 lished, I had been engaged for seven years in the development of flying models. 

 Although the work was discouraging and often resulted in failure, success was 

 finally reached under the conditions just referred to, which obviously admitted 

 of its being reached again, and on a larger scale, if desired. 



'Communication to the French Academy. Extract from the Comptes Rendus of the Sessions of 

 the Academy of Sciences. Vol. 122, Session of May 26, L896. 



(Translation.) 

 A Description of Mechanical Flight. By S. P. Langley. 



In a communication which I addressed to the Academy in July. 1891, I remarked that the results 

 of experimental investigation had shown the possibility of constructing machines which could give 

 such a horizontal velocity to bodies resembling in shape inclined planes, and more than a thousand 

 times heavier than air. that these could be sustained on this element. 



While I have elsewhere remarked that surfaces other than planes might give better results, 

 and that absolutely horizontal flight, which is so desirable in theory, is hardly realizable in 

 practice, so far as I know there has never heen constructed, up to the present time, any heavy 

 aerodrome, or so-called flying-machine, which can keep itself freely in the air by its own force more 

 than a few seconds, the difficulties encountered in absolutely free flight being, for many reasons, im- 

 measurably greater than those experienced when the flight is controlled by the body's pressing 

 upward against a horizontal track, or whirling-arm. No one is unaware that many experimenters 

 have been engaged in trying to execute free mechanical flight, and although the demonstration 

 which I furnished in 1S91 [" Experiments in Aerodynamics," 1S91] of its theoretical possibility with 

 means then at our disposition, seemed conclusive, so long a time has elapsed without practical results, 

 that it might be doubted whether these theoretical conditions are to be realized. I have thought it 

 well, then, to occupy myself with the construction of an aerodrome with which I might put my 

 previous conclusions to the test of experiment. 



The Academy will, perhaps, find it interesting to read the narrative given here by an eye-witness, 

 who is well known to it. I am led to present it not only by the request with which he honors me. 

 but by the apprehension that my administrative duties may put a stop to these researches, so that 

 it seems to me advisable to announce the degree in which I have already succeeded, although this 

 success be not as complete as I should like to make it. 



The experiments took place on a bay of the Potomac River, some distance below Washington. 

 The aerodrome was built chiefly of steel, though lighter material entered into the construction, so 

 that its density as a whole was a little below unity. No gas whatever rntered into the construction of 

 the machine, and the absolute weight, independent of fuel and water, was about 11 kilos (24 pounds). 

 The width of the supporting surfaces was about 4 metres (13 feet), and the power was furnished by 

 an extremely light engine of approximately one horse-power. There was no one to direct it on 

 board, and the means for keeping it automatically in horizontal flight were not complete. It is 



