- MrcroGRraPHini T65 
and corrodes thofe tender fibres: As I have thewed in the defeription 
‘ofa Nettle and of Cowhage. - nib 
ry ee 
Sar’ 
Obferv. XX XV. Of the contexture and rape of the barbiches of 
’ Feathers. | bas 1guol cog atods 
¥>Xamining feveral forts of Feathers, I took notice of thefe particulars 
E in all forts of wing-Feathers, efpecially in thofe which ferv'd for the 
beating of the air in the actionof flying. | ret Heo ver 
That the outward farface of the Quill and Stern was ofa very hard, ftiff, 
‘and horny fubftance, which is obvidus enougli, and that the part above 
the Quill was fill'd with a very white and light pith, and, with the Adicro- 
cope, { found this pith to be nothing elfe, but a kind of natural congerzes 
of fmall bubbles,the films of which feem to be of the fame fubftance with 
that of the Quill, thavis, of a (tiff tranfparent horny fubftance. 
- Which particular feems to me,very worthy a more ferious confiderations 
For here we may obferve Nature,as ‘twere,put to its fhifts, to make a fub= 
ftance,which fhall be both light enough,and very {tiffand ftrong,without 
varying from its own eftablifh’d principles, which wemay obferve to be 
" flich, that very ftrong bodies are’ forthe moft part very heavie alfo, a 
ftrength of the parts ufually requiring adenfity, anda denfity.a cans 
and therefore fhould Nature have made a body fo broad and: fo itrong as | 
a Feather, almoft, any other way then what it has taken, the pravity of it 
muft necefiarily have many times exceeded this for this pith feems to be 
like fo many ftops or crofs pieces in a long optical tube, which do very 
much contribute to the ftrength of the whole, the pores of which were 
fisch, as that they feem’d not to have any communication with one ano- 
ther, as I have elfewhere hinted. , 40 
But the Mechanifm of Nature is ufually fo excellent, that one and the 
fame {ubftance is adapted to ferve for many ends.) For the chief ufe of 
this, indeed, feems to be for the fupply of nourifhment to the downy or 
feathery part of the ftem; for’tis obvious enough in all forts of Feathers, 
that ‘tis plac’d juft under the roots of the branches that grow out of ¢i+ 
ther fide of the quill of ftalk, and is exa@tly thap'd according to the rank- 
ing of thofe baicches coming no lower into the quill, then juft the be- 
ginning of the downy branches, and growing onely on the under fide of 
Of the quill where thofe branches dof. ‘Now, in a ripe Feather (asone 
may cull it) it (ems difficultto conceive how the Swccus musritius fhould 
I think, be well imagin’d to pa 
lainly enough perceive the Veflel for the conveyance oF It fe” 
filmy ~¢ (as tiscall'd) which pafles through the middle of pote . 
Astor the make and coritexture of the Down it elf; it is indee 2a 
