vii FLIGHT 267 



damaged by the fact that Mr. Maxim's flying machine, 

 weighing 3.^- tons (a very heavy bird !), has actually 

 risen from the ground. It is true that all the giant 

 fossil birds that have been discovered seem to have 

 been allies of the Ostrich and incapable of flight. 

 Since, however, the geological record is not only 

 imperfect but has, much of it, still to be read, we 

 cannot say that giant flying birds never existed. 

 Supposing that they once existed, they may have died 

 out for reasons not connected with flight. Many large 

 mammals and reptiles have become extinct, the 

 smaller having some advantage in the race of life. 



When we come to compare the actual achievements 

 of big and small birds, it will be found that the 

 honours are divided. The small can rise with greater 

 ease, the line of ascent being far nearer to the vertical. 

 This may in many cases be due to the greater stiffness 

 of the shoulder-joint in large birds, which prevents 

 the wing turning its under surface backward, as it 

 must turn for ascent up a steep incline (see above on 

 upward flight). But in one of the big birds that I 

 have examined, the Eagle, 1 this stiffness is not found. 

 If we concede that small birds rise with less effort, 

 on the other hand, the big are, I believe, even allowing 

 for their greater bulk, better weight-carriers. An 

 Eagle will carry a young lamb ; for a House Sparrow a 

 very small piece of bread is a heavy burden. 



In long-distance flight the two classes are about 

 equally matched. 



Small birds never soar, and it is generally supposed 



1 It can rise with greater ease, I think, than many big sea- 

 birds that are stiff at the shoulder. 



