28 
REACTIVE LOCOMOTION. 
preflures originate not in the bird but in the vaft magazines 
of external nature. 
It feems prefumptuous for any man to fay, “ I have 
difcovered what mankind during thoufands of years have 
fought for in vain ! ” And it is prefumptuous. Therefore 
I will not fay I have difcovered. If any man could have 
difcovered the fecret of flying, Pettigrew, I think, is the 
man, for he comes nearer to it than any other; and yet, 
ftrange to fay, he attempts to controvert the theory of 
Borelli, who wrote in 1680 on the action of the wings, 
and of Profeflor Marey, who wrote in 1869 advocating 
Borelli’s theory becaufe fubftantiated by his own experi¬ 
ments ; both Borelli and Marey being quite right, and 
Pettigrew quite wrong. Neverthelefs, Pettigrew, in his 
book cc Animal Locomotion,” has enunciated more found 
philofophy on the fubjed: of flying, and has fhown a 
deeper inflght into the true principles of bird performances, 
than any other writer whofe views have fallen under my 
eye. Take for example the following:— 
“ The wing of a flying creature, as I have taken pains 
to fhow, is not rigid; neither does it always ftrike the air 
at a given angle. On the contrary, it is capable of moving 
in all its parts, and attacks the air at an infinite variety of 
angles. Above all, the furface expofed by a natural wing, 
when compared with the great weight it is capable of 
elevating, is remarkably fmall. This is accounted for by 
the length and the great range of motion of natural wings, 
