tude 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 oft-times 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.
These threads therefore I find to be a congeries of small Lamina or plates, as e e e e e, &c. each of them shap’d much like this of a b c d, in the fourth Figure, the part a c being a ridge, prominency, or stem, and b and d the corners of two small thin Plates that grow unto the finall stalk in the middle, so that they make a kind of little feather; each of these Plates lie one close to another,almost like a company of sloping ridge or gutter Tyles; they grow on each side of the stalk opposite to one another, by two and two, from top to bottom, in the manner express’d in the fifth Figure, the tops of the lower covering the roots of the next above them; the under side of each of these laminated bodies, is of a very dark and opacous substance, and suffers very few Rays to be trajected, but reflects them all toward that side from whence they come, much like the foil of a Looking-glass; but their upper sides seem to me to consist of a multitude of thin plated bodies, which are exceeding thin, and lie very close together, and thereby, like mother of Pearl shells, do not onely reflect a very brisk light, but tinge that light in a most curious manner; and by means of various positions, in respect of the light, they reflect back now one colour, and then another, and those most vividly.
Now, that these colours are onley fantastical ones, that is, such as arise immediately from the refractions of the light, I found by this, that water wetting these colour’d parts,destroy’d their colours, which seem'd to proceed from the alteration of the reflection and refraction. Now, though I was not able to see those hairs at all transparent by a common light, yet by looking on them against the Sun, I found them to be ting’d with a darkish red colour, nothing a-kin to the curious and lovely greens and blues they exhibited.
What the reason of colour seems to be in such thin plated bodies, I have elsewhere shewn. But how water cast upon those threads destroys their colours, I suppose to be perform’d thus; The water falling upon these plated bodies from its having a greater congruity to Feathers then the Air, insinuates it self between those Plates, and so extrudes the strong reflecting Air, whence both these parts grow more transparent, as the Microscope informs, and colourless also, at best retaining a very faint and
