BIRD-FLTING. 
S 1 
tures float, and through which not only flying but all other 
creatures move, demands, becaufe of its forceful character, 
fpecific gravities in the creatures of a character analogous 
to what I have supposed would be the required weight and 
fpecific gravity of water-breathing creatures inhabiting a 
water-fphere penetrated with the tremendous forces that 
are ftored up and difcharged continually through all the 
fpaces underneath our fkies. 
The difficulties of air-locomotion do not inhere in the 
non-force character of the air in its eight hundred times 
lefs denfity than water, and the fpecific gravity of the 
bodies of the creatures that live in it; but in the force- 
atmofphere that furrounds them. 
It is not, therefore, practically fpeaking, the air that is 
eight hundred times lighter than man’s weight and birds 5 
weight (I admit fomething lefs for birds) that we have to 
deal with in the problem of bird-flying, but the Force - 
Atmofphere enclofed, fo to fpeak, within the atmofphere 
we breathe. 
This force-atmofphere is the bird-atmofphere, for 
which the creature is made and adapted, with reference 
to which his marvellous wings are made lights and his 
body made heavy ; a body to fink it, and wings to raifie 
it; two oppofing agents giving rise to two oppofing 
forces: the one a counteracting agent to the other, and 
yet confpiring to a common end; a mechanifm and a 
combination of forces to meet and battle with, and over- 
