744 THE POPULAR SCIENCE MONTHLY. 



NEW LIGHTS ON THE PROBLEM OF FLYING. 



BY PBOF. JOSEPH LE CONTE. 



SOME of the readers of The Popular Science Monthly may re- 

 member that in November, 1888, I published an article in 

 which I tried to show the physical impossibility of a true flying 

 machine i. e., one which could both lift and propel itself without 

 the help of a balloon. The article was widely commented upon, 

 the only objection urged being the threadbare one that more won- 

 derful things than this have come to pass and will come to pass 

 again. Since that time, however, a very elaborate series of ex- 

 periments by Prof. Langley has thrown so much and so new light 

 on the whole problem of flying, that I am forced to reconsider 

 and modify somewhat the conclusions then reached. Having 

 been asked to contribute a paper on the subject of flying to the 

 World's Congress of Aeronautics, I, a few months ago, reviewed 

 the whole subject in the light of these new experiments. The 

 pressure of other duties at that time prevented me from putting 

 my thoughts in final form, and I laid aside my notes. But I feel 

 that I owe it to myself, as well as to The Popular Science Month- 

 ly, that I should again express my views under the changed con- 

 ditions. This article, therefore, may be regarded as substantially 

 what I would have given at the World's Congress if I had had 

 time then to prepare it. 



But this time I find it necessary to take up the subject from a 

 more general point of view than before. My theme now is the 

 problem of flying, both natural and artificial. I begin, therefore, 

 with some discussion of the flight of birds. 



The bird's wing has two distinct functions, viz., that of a pro- 

 peller and that of an aeroplane. Both of these functions are per- 

 formed by the wing in ordinary flight, but in different relative 

 proportions according to the size of the bird and the extent of its 

 wings. In insects and in small birds the wings act almost wholly 

 as propellers. In large birds with great expanse of wings, ex- 

 cept in rising, they act mainly as an aeroplane. This difference 

 between small and large birds is fully recognized in my previous 

 paper, but I did not then appreciate its supreme importance. 

 Now it is on the properties of an aeroplane that the new light has 

 been mainly shed, and it is therefore of its function in flight that 

 I shall have most to say. First, however, a very few words on the 

 bird's wing as a propeller. 



The structure of a bird's wing is a marvel of exquisite con- 

 trivance a wonderful combination of lightness, elasticity, and 

 strength. The hollow quill, the tapering shaft, the vane com- 

 posed of barbs clinging together by elastic hooks, making thus an 



