DIVING BIRDS AT THE ZOO 
83 
flight indifferently, but the feet are also used in turn- 
ing, and the wing-strokes are more sustained, regular, 
and slower than in the case of the true “ seal-birds.” 
As an “ all-round performer,” the guillemot is perhaps 
the best in the Zoological Society’s collection, and 
with the whole of the upper plumage, head and neck, 
converted by a “ sea-change” into what appears a 
clinging mantle of quicksilver, it is certainly the most 
beautiful in its favourite element. The “ air-jacket ” 
which the guillemot carries with it after each dive, 
and which, gradually vanishing in the water, is 
renewed after its rise to the surface to breathe or 
swim, probably plays a useful part in its submarine 
flights. It lessens the surface friction of the water, 
and, like the air below the “ skimming-dish ” boat, 
which some inventors look upon as the probable 
means of obtaining the next considerable rise of 
speed on the surface, is the simplest and most natural 
of all lubricants between the bird and the water. 
The other birds in the cages are perhaps more 
truly classed as divers than the penguins and their 
relations. They plunge and swim, using their wings 
for aerial flight only. 
Those who watch the cormorant’s diving feats are 
usually so interested in the fortunes of the chase as 
the handsome bird dashes after the fish, that not 
one visitor in twenty observes that, from the mode 
of its entering the water to its exit, its methods of 
movement are absolutely different to those of the 
penguins. The cormorant does not plunge headlong. 
