400 
POPULAR SCIENCE REVIEW. 
opinion by reference to some long-winged birds that effect their 
rise from the ground, not alone by extending the wings as 
planes, but by using the air as a fulcrum which is increased in 
solidity by the multiplication of the vibratory wing-action. 
Mr. F. H. Wenham, in the first paper read before the Aero- 
nautical Society, speaks of the eagle which he sees sitting in 
solitary state in the midst of an Egyptian plain. 
“ An approach to within eighty yards arouses the king of 
birds from his apathy. He partly opens his enormous wings, 
but stirs not yet from his station. On gaining a few feet more, 
he begins to walk away. Now for the chance fire. A charge 
of No. 3 from 11 bore rattles audibly but ineffectually upon 
his densely feathered body. His walk increases to a run, he 
gathers speed with his slowly waving wings, and eventually 
leaves the ground. Rising at a gradual inclination, he mounts 
aloft, and sails majestically away to his place of refuge in the 
Lybian range, distant at least five miles from where he rose. 
Some fragments of feathers denote the spot where the shot had 
struck him. The marks of his claws are traceable in the sandy 
soil, as at first with firm and decided digs he forced his way, 
but as he lightened his body and increased his speed with the 
aid of his wings, the imprints of his talons gradually merged 
into long scratches. The measured distance from the point 
where these vanished to the place where he had stood, proved 
that, with all the stimulus that the shot must have given to his 
exertions, he had been compelled to run full twenty yards before 
he could raise himself from the earth.” 
Thus Nature teaches us ; but there is such an infinite variety 
in the mode of flight, and in the manner of progression, both in 
water and in air, that though we may never get the proverbial 
pig to fly, we may possibly be able widely to depart from any 
known form. 
The difficulties which inventors have foreseen, and sometimes 
encountered without foresight, are — the construction of wings 
which shall be of the great lateral extension considered to be 
necessary ; — strength of structure ; — ability to manipulate them. 
The preservation of a certain amount of rigidity throughout 
the whole length, decreasing towards the tips, and especially so 
between the anterior and posterior portions of the wings’ edges 
— the great strain upon the posterior edge, which cannot be 
framed to any attachment without destroying the whole prin- 
ciple of action — and the small amount of sustaining surface by 
reason of the comparative narrowness of wing, under which it 
is impossible to see safety unless by the preservation of an 
acrobatic balance. 
All these considerations have militated against the employ- 
ment of wings for progression and support upon the air. 
