170 ON THE DIVING OF AQUATIC BIRDS. 
wings of Diving Fowls are placed so forward: 
doubtless not for the purpose of promoting their 
speed in flying, since that position certainly impedes 
it; but probably for the increase of their motion 
under water, by the use of four oars instead of two; 
yet were the wings and feet nearer together, as in 
land birds, they would, when in action, rather hinder 
than assist one another.” 
Mr. White’s description of the manner in which 
the Northern Diver impels itself through the water 
by the agency of the legs, which have an extent 
of motion enabling it to alter its course in any 
direction whatever with astonishing facility, is ap- 
plicable to Diving Birds in general; but it does 
not appear that the wings are so uniformly employed 
to promote their progress, when submerged, as the 
statement of the natural historian of Selborne would 
seem to imply. 
I may remark, in conclusion, that the action of 
the legs in diving, so far from giving birds an im- 
pulse upwards and forwards, as Montagu has affirmed, 
evidently tends rather to propel them downwards 
and forwards, except when they purpose to ascend, 
and then a change of action, adapted to the accom- 
plishment of the object to be attained, is instantly 
resorted to. The simultaneous action of the legs 
also, directing the impelling power in the line of 
the body, will explain why the velocity with which 
Aquatic Birds move in so dense a fluid as water is 
