From which strange contexture, it seems rational to suppose that there is a certain kind of mesh or hole so small, that the Air will not very easily pass through it, as I hinted also in the sixth Observation about small Glass Canes, for otherwise it seems probable, that Nature would have drawn over some kind of thin film which should have covered all those almost square meshes or holes, there seeming through the _Microscope_ to be more then half of the surface of the Feather which is open and visibly pervious; which conjecture will yet seem more probable from the texture of the brushie wings of the _Tinea argentea_, or white Feather wing’d moth, which I shall anone describe. But Nature, that knows best its own laws, and the several properties of bodies, knows also best how to adapt and fit them to her designed ends, and whoso would know those properties, must endeavour to trace Nature in its working, and to see what course she observes. And this I suppose will be no inconsiderable advantage which the _Schematisms_ and Structures of Animate bodies will afford the diligent enquirer, namely, most sure and excellent instructions, both as to the practical part of _Mechanicks_ and to the _Theory_ and knowledge of the nature of the bodies and motions. * * * * * Observ. XXXVI. _Of _Peacocks_, _Ducks_, and other _Feathers_ of changeable colours._ The parts of the Feathers of this glorious Bird appear, through the _Microscope_, no less gaudy then do the whole Feathers; for, as to the naked eye ’tis evident that the stem or quill of each Feather in the tail sends out multitudes of _Lateral_ branches, such as AB in the third Figure of the 22. _Scheme_ represents a small part of about ¹⁄₃₂ part of an Inch long, and each of the _lateral_ branches emit multitudes of little sprigs, threads or hairs on either side of them, such as CD, CD, CD, so each of those threads in the _Microscope_ appears a large long body, consisting of a multitude of bright reflecting parts, whose Figure ’tis no easie matter to determine, as he that examines it shall find; for every new position of it to the light makes it perfectly seem of another form and shape, and nothing what it appear’d a little before; nay, it appear’d very differing ofttimes from so seemingly inconsiderable a circumstance, that the interposing of ones hand between the light and it, makes a very great change, and the opening or shutting a Casement and the like, very much diversifies the appearance. And though, by examining the form of it very many ways, which would be tedious here to enumerate, I suppose I have discover’d the true Figure of it, yet oftentimes, upon looking on it in another posture, I have almost thought my former observations deficient, though indeed, upon further examination, I have found even those also to confirm them.