EVIDENCE OF DESIGN. 129 
retains its resiliency and all its flexibility for years—all 
that is necessary is to keep it dry. It is finished all along 
the rib (or quill) with a hard, glossy enamel on the out- 
side and this enamel keeps its polish as long as the feather 
lasts. 
From an engineering standpoint, or the standpoint of 
the mechanic or artisan, there is absolutely no suggestion 
of betterment to be made, for the feather is an exact, per- 
fectly finished product. Its long central quill tapers from 
base to point with geometric precision, thereby giving per- 
fect resistance to bending force, and this is one of the 
combination of secrets that enables the bird to fly as 
easily as man can walk. Also this long quill is hollow, 
thereby all extra weight is done away with and added 
streneth gained because of the tube contruction; and to 
make it perfect from a mechanical standpoint, the under 
side of the quill is reinforced by a doublerolled thickening 
of the shell of the quill itself so that strains are equalized. 
“This long quill is also curved slightly, to meet air 
resistance again and overcome it when the whole tail is 
spread, fan-like, to suddenly alter a direction or check 
speed in flight. 
“The long, soft side masses are formed of a multitude 
of tiny feathers, each one perfectly equipped, perfectly 
made, mechanically and geometrically without fault. 
Each of these tiny side feathers has its own midrib that 
tapers from base to tip, and each of these midribs carries 
its own equipment of side ‘hairs’ so beautifully constructed 
that it locks automatically into the one on each side of it 
in such a way that it makes a solid yet flexible mass of 
the whole surface, against which the air flows as the bird 
flies. 
“Tf these side feathers be split apart they will come 
back into place so exactly that the split cannot be de- 
tected. Nothing else in nature repairs itself with such 
