PKOGRESSION ON AND IN THE WATER. 



95 



For the same reason, she has furnished the diving bird with 

 a certain degree of buoyancy, and the flying bird with a cer- 

 tain amount of weight- — levity tending to bring the one to 

 the surface of the water, weight the other to the surface of 

 the earth, which is the normal position of rest for both. The 

 action of the subaquatic or diving wing of the king penguin 

 is well seen at p. 94, fig. 47. 



From what has been stated it will be evident that the 

 wing acts very differently in and out of the water ; and this 

 is a point deserving of attention, the more especially as it 

 seems to have hitherto escaped observation. In the water 

 the wing, when most eff*ective, strikes downwards and bachvards, 

 and acts as an auxiliary of the foot ; whereas in the air it 

 strikes downwards and forwards. The oblique surfaces, spiral 

 or otherwise, presented by animals to the water and air are 

 therefore made to act in opposite directions, as far as the 

 down strokes are concerned. This is owing to the greater 

 density of the water as compared with the air, — the former 

 supporting or nearly supporting the animal moving upon or 

 in it ; the latter permitting the creature to fall through it in a 

 downward direction during the ascent of the wing. To coun- 

 teract the tendency of the bird in motion to fall downwards 

 and forwards, the down stroke is delivered in this direction ; 

 the kite-like action of the wing, and the rapidity with which 

 it is moved causing the mass of the bird to pursue a more 

 or less horizontal course. I offer this explanation of the 

 action of the wing in and out of the water after repeated and 

 careful observation in tame and wild birds, and, as I am 

 aware, in opposition to all previous writers on the subject. 



The rudimentary wings or paddles of the penguin (the 

 movements of which I had an opportunity of studying in a 

 tame specimen) are principally employed in swimming and 

 diving. The feet, which are of moderate size and strongly 

 webbed, are occasionally used as auxiliaries. There is this 

 difference between the movements of the wings and feet 

 of this most curious bird, and it is worthy of attention. 

 The wings act together, or synchronously, as in flying birds ; 

 the feet, on the other hand, are moved alternately. The 

 wings are wielded with great energy, and, because of their 



