AERIAL MANCEUVRES. 
337 
in the old magic and the philosophy of the Cabala. It is more to the 
purpose to say that the wedge-form is well adapted for attack, as well 
as resistance; and for this reason, probably, has been intuitively 
adopted by the swans, geese, ducks, and other migratory birds. 
Cicero, in his " Natura Deorum," has an ingenious passage, in which 
he explains that the order of march of the cranes is so arranged that 
the rear-guard pushes forward the corps de bataille. Whether the 
Roman philosopher's reasons are wholly satisfactory, may be doubted; 
but it seems probable that, from the perpetual displacements which 
occur in the ranks of all birds whose flight describes a triangle, or 
rather an acute angle, the most difficult post is that of the apex of the 
angle. The bird who occupies it has to cleave the current of air and 
carve out a path, so to speak, for those who follow him. Therefore 
it is that, when his wings ai'e exhausted by the continuous effort, he 
gives place to another, and falls back into the rear-guard. It has been 
observed that the soldiers in the central or main body are not affected 
by these manoeuvres ; and hence we conclude that the intermediate 
ranks are composed of young birds, and that the adults arrange them- 
selves in such a manner as to relieve them of all difficulty and exertion. 
This is not the only instance of fraternity and prudence which the ways 
and manners of the cranes present to the careful investigator. 
The ancients, if not very accurate, were at all events very loving 
observers of the aspects of Nature, and especially of the flight of birds. 
They were of opinion that the cranes never abandoned their triangular 
array except on the occurrence of some grave atmospheric perturbation, 
or the appearance of the eagle, their formidable enemy. And on this 
slender basis of fact they founded numerous airy structures of Action, 
which have amused the credulity of the moderns. For example: they 
pretended that when the cranes of the lands bordering on the Euxine 
approached the Taurus mountains, which interpose on the route from 
Thrace and Scythia into Egypt, where they spent the winter, the fear 
of falling into the clutches of the eagles which people that great chain 
made them adopt the most notable precautions. A first order of the 
day prohibited diurnal marches ; a second required every one of the 
nocturnal convoy to take a pebble in his beak, eff"ectually to prevent 
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