2 26 The Smithsonian Institution 



soluble as theretofore affirmed by many of the most eminent 

 scientific men. 



"Whether Doctor Langley's scientific labors in this depart- 

 ment of physics will soon result, like those of the preceding 

 Secretaries, in the practical application of his discoveries to 

 the use of mankind, it is perhaps too early to assert positively, 

 I think, myself, that they will so result before many years, but 

 there are so many intricate questions to be solved before com- 

 mercial success can be achieved that another generation may 

 pass before the problem of flight is fully solved. 



" Moreover, Doctor Langley's labors and discoveries are 

 by no means over. He has thus far published only the 

 result of his investigations on planes, while saying in 

 the penultimate paragraph of his summary that it is not 

 asserted that planes are the best forms to use. Lilienthal 

 and Phillips have since shown that concave-convex surfaces 

 are more efficient forms, and it is very much to be desired 

 that Doctor Langley shall next publish some data concerning 

 such forms. 



"The practical development of a scientific truth is some- 

 what like the growth from a new seed. We recognize the 

 existence of the plant, we ascertain some of its virtues, but 

 we cannot tell its full uses, how soon it will mature, nor how 

 large the tree will be. 



" It is significant, however, that, prior to the publication of 

 Doctor Langley's work, it was the rare exception to find 

 engineers and scientists of recognized ability who would fully 

 admit the possibility of man being able to solve the twenty- 

 century old problem of aviation. Professor Joseph Le Conte, 

 in the Popular Science Monthly of November, 1888, has 

 very recently taken the ground, flatly, ' that a pure flying 

 machine is impossible.' This was probably based on the fact 

 that the then accepted formula of Newton, and the calculation 

 of Napier and other scientists, if correct, rendered the solution 

 practically impossible. Since the publication of 'Experiments 

 in Aerodynamics,' however, it is the exception to find an in- 

 telligent engineer who disputes the probability of the eventual 

 solution of the problem of man-flight. Such has been the 



