CHAPTER XII 

 THE BODY OF A BIRD 



N experimenting with balloons and flying-ma- 

 chines, weight is a question of prime im[)ort- 

 ]\ ance, and among birds there seem to be certam 

 limits to the bulk of the body, beyond which flight is 

 impossible. The tiny hummingbirds, with bodies weigh- 

 ing less than some insects, have remarkable powers of 

 flight, and throughout all the groups of larger birds we 

 find certain species with exceptional flight ability, until 

 in the birds of widest extent of wing, such as the condor 

 and the albatross, flight seems to reach the acme of perfec- 

 tion. But the flying birds of actual heaviest bulk are 

 perhaps the Wild Turke}', the Great Bustard, and the 

 Trumpeter Swan, the two latter reaching weights of thirty- 

 two and twenty-five pounds respectively. Even the 

 gigantic Pterodactyls, those flying reptiles of olden time, 

 some of which had heads a yard long, and an expanse of 

 eighteen feet or more of bat-like wings, are estimated 

 to have weighed but twenty pounds or thereabouts. 



But when the necessity for flight ceases, a bird may 

 begin to assume larger proportions and greater weight 

 without detriment; just as a mammal which adopts a life 



in the dense medium of water may attain a much more 



285 



