Makch 4, 1910] 



SCIENCE- 



335 



memoir entitled, "Experiments in Aero- 

 dynamics. ' ' 



In this work he laid the foundations for 

 a science and art of aerodromics; and 

 raised the whole subject of aerial flight to 

 a scientific plane. 



The knowledge that this eminent man of 

 science believed in the practicability of 

 human flight gave a great stimulus to the 

 activities of others, and started the modern 

 movement in favor of aviation that is such 

 a marked feature of to-day. 



Every one now recognizes the infltience 

 exerted by Langley on the development of 

 this art. The "Wright Brothers too have 

 laid their tribute at his feet. They say: 



The knowledge that the head of the most promi- 

 nent scientific institution of America believed in 

 the possibilty of human flight was one of the 

 influences that led us to undertake the prelim- 

 inary investigations that preceded our active 

 work. He recommended to us the books which 

 enabled us to form sane ideas at the outset. It 

 was a helping hand at a critical time, and we 

 shall always be grateful. 



CONTRIBUTIONS TO THE SCIENCE OP 

 AERODROMICS 



Langley 's experiments in aerodynamics 

 gave to physicists, perhaps for the first 

 time, firm ground on which to stand as to 

 the long-disputed questions of air resist- 

 ances and reactions. Chanute says: 



(a) They established a more reliable coefficient 

 for rectangular pressures than that of Smeaton. 



(6) They proved that upon inclined planes the 

 air pressures were really normal to the surface. 



(c) They disproved the " Newtonian Law," that 

 the normal pressure varied as the square of the 

 angle of incidence on inclined planes. 



(d) They showed that the empirical formula of 

 Duchemin, proposed in 1836 and ignored for fifty 

 years, was approximately correct. 



(e) That the position of the center of pressure 

 varied with the angle of inclination, and that on 

 planes its movements approximately followed the 

 law formulated by Joessel. 



(f) That oblong planes, presented with their 

 longest dimension . to the line of motion, were 



more effective for support than when presented 

 with their narrower side. 



(g) That planes might be superposed without 

 loss of supporting power if spaced apart certain 

 distances which varied with the speed. 



(h) That thin planes consumed less power for 

 support at high speeds than at low speeds. 



The paradoxical result obtained by 

 Langley that it takes less power to support 

 a plane at high speed than at low, opens 

 up enormous possibilities for the aerodrome 

 of the future. It results, as Chanute has 

 pointed out, from the fact that the higher 

 the speed, the less need be the angle of 

 inclination to sustain a given weight, and 

 the less therefore the horizontal component 

 of the air pressure. 



It is true only, however, of the plane 

 itself; and not of the struts and frame- 

 work that go to make up the rest of a flying 

 machine. In order therefore to take full 

 advantage of Langley 's law, those portions 

 of the machine that ofi^er head resistance 

 alone, without contributing anything to the 

 support of the machine in the air, should 

 be reduced to a minimum. 



CONTRIBUTIONS TO THE ART OF AERODROMICS 



After laying the foundations of a science 

 of aerodromics, Langley proceeded to re- 

 duce his theories to practise. 



Between 1891 and 1895 he built four 

 aerodrome models ; one driven by carbonic 

 acid gas, and three by steam engines. 



On May 6, 1896, his "Aerodrome No. 5" 

 was tried upon the Potomac River near 

 Quantico. I was myself a witness of this 

 celebrated experiment; and secured photo- 

 graphs of the machine in the air, which 

 have been widely published.^ 



This aerodrome carried a steam engine, 

 and had a spread of wing of from twelve 

 to fourteen feet. It was shot into the air 

 from the top of a house-boat anchored in a 

 quiet bay near Quantico. 



"A photograph of this flight was here shown. 



