THE PROBLEM OF A FLYING-MACHINE. 



75 



The reason of this -wonderful effectiveness of the animal ma- 

 chine is obvious. See how this machine has been gradually per- 

 fected throughout infinite ages, especially in birds. During the 

 whole geological history of the earth this machine has been stead- 

 ily improving in structure of skeleton, energy of muscle, and 

 rapidity of combustion of fuel, by struggle for life and survival 

 of only the swiftest, the most energetic, and the hottest-blooded, 

 until an almost incredible intensity is reached in birds. More- 

 over, in them everything is sacrificed to the supreme necessity of 

 flight. Viscera, skeleton, legs, head, all are made as small and 

 light as possible to make room for the great pectoral muscles 

 working the wings. Add to this the exquisite structure of the 

 wings and feathers, adapting them for the greatest effectiveness ; 

 and we must admit that a bird is an incomparable model of a 

 flying-machine. No machine that we may hope to devise, for 

 the same weight of machine, fuel, and directing brain, is half so 

 effective. And yet, this machine thus perfected through infinite 

 ages by a ruthless process of natural selection, reaches its limit of 

 weight at about fifty pounds ! I said, " weight of machine, fuel, 

 and directing brain," Here is another prodigious advantage of 

 the natural over the artificial machine. The flying animal is its 

 own engineer, the flying-machine must carry its engineer. The 

 directing engineer in the former (the brain) is perhaps an ounce, 

 in the latter it is one hmidred and fifty pounds. The limit of the 

 flying animal is fifty pounds. The smallest possible weight of a 

 flying-machine, with its necessary fuel and engineer, even without 

 freight or passengers, could not be less than three or four hundred 

 pounds. 



Now, to complete the argument, put these three indisputable 

 facts together : 1. There is a low limit of weight, certainly not 

 much beyond fifty pounds, beyond which it is impossible for an 

 animal to fly. Nature has reached this limit, and with her utmost 

 effort has failed to pass it. 3. The animal machine is far more 

 effective than any we may hope to make ; therefore the limit of 

 the weight of a successful flying-machine can not be more than 

 fifty pounds. 3. The weight of any machine constructed for fly- 

 ing, including fuel and engineer, can not be less than three or four 

 hundred pounds. Is it not demonstrated that a true flying-ma- 

 chine, self-raising, self-sustaining, self -propelling , is physically 

 impossible ? 



6. Application to a Swimming-Machine. — But is there not 

 a way of escape from the toils of this inexorable logic ? We 

 have said the limit of the weight of a flying animal is about fifty 

 pounds. The limit for a walking animal is much higher, probably 

 several tons. For a swimming animal there is no limit of iveight 

 and size, because the water sustains the weight, and therefore the 



