THE LANGLEY AERODROME. 205 



First t'onu's the humorus, or prineijDal bone of the upper arm, which 

 is in the wing- also (PI. 1). Next we see that the forearm of the bird 

 repeats the radius and ubui, or two bones of our own forearm, while 

 our wrist and finger bones are modified in the bird to carry the feathers, 

 but are still there. To make the bird, then, nature appears to have 

 taken what material she had in stock, so to speak, and developed it 

 into something that would do. It was all that nature had to work on, 

 and she has done wonderfully well with such unpromising- material; 

 but an3'one can see that our arms would not be the best thing to make 

 flying machines out of, and that there is no need of our starting there 

 when we can start with something l)etter and develop that. Flapping 

 wings might be made on other principles, and perhaps will be found 

 in future flying machines, but the most promising thing to try seemed 

 to me to l)e the screw propeller. 



Some twent}" years ago, Penaud, a Frenchman, made a toy, consist- 

 ing of a flat, immovable, sustaining wing surface, a flat tail, and a 

 small propelling screw. He made the wing and tail 

 out of paper or silk, and the propeller out of cork I 

 and feathers, and it was driven directly b}'^ strands of | 

 india-ru))))er twisted lamplighter fashion, and which ^ ' "v. 

 turned the wheel as they untwisted. L J 



The great difficulty of the task of creating a flying yN. 



machine may be partly understood when it is stated <^^^0 

 that no machine in the w^hole history of invention, pgn^uds flying toy 

 unless it were this toy of Penaud's, had ever, so far as (one-eighth of ac- 

 I can learn, flown for even ten seconds; but something 

 that will actually fly must be had to teach the art of "balancing." 



When experiments are made with models moving on a whirling 

 table or running on a railroad track, these ^yq forced to move horizon- 

 tally and at the same time are held so that thej^can not turn over; but 

 in free flight there will be nothing to secure this, unless the air ship 

 is so adjusted in all its parts that it tends to move steadily and hori- 

 zontally, and the acquisition of this adjustment or art of "balancing" 

 in the air is an enormously difficult thing, and which, it will be seen 

 later, took years to acquire. 



My first experiments in it, then, were with models like these, but 

 from them I got only a rude idea how to balance the future aero- 

 drome, partly on account of the brevity of their flight, which only 

 lasted a few seconds, partly on account of its irregularity. Although, 

 then, much time and labor were spent by me on these, it was not pos- 

 sible to learn much about the balancing from them. 



Thus it appeared that something which could give longer and steadier 

 flights than india rubber must be used as a motor, even for the prelim- 

 inary trials, and calculations and experiments were made upon the use 

 of compressed air, carbonic-acid gas, electricity in primary and storage 



