and therefore Nature has furnish'd his foot with another
_additament_ much more curious and admirable, and that is, with a couple of
Palms, Pattens or Soles DD, the structure of which is this:

From the bottom or under part of the last joint of his foot, K, arise two
small thin plated horny substances, each consisting of two flat pieces, DD,
which seem to be flexible, like the covers of a Book, about FF, by which
means, the plains of the two sides EE, do not always lie in the same plain,
but may be sometimes shut closer, and so each of them may take a little
hold themselves on a body; but that is not all, for the under sides of
these Soles are all beset with small brisles, or tenters, like the Wire
teeth of a Card used for working Wool, the points of all which tend
forwards, hence the two Tallons drawing the feet forwards, as I before
hinted, and these being applied to the surface of the body with all the
points looking the contrary way, that is, forwards and outwards, if there
be any irregularity or yielding in the surface of the body, the Fly
suspends it self very firmly and easily, without the access or need of any
such Sponges fill'd with an imaginary _gluten_, as many have, for want of
good Glasses, perhaps, or a troublesome and diligent examination, suppos'd.

Now, that the Fly is able to walk on Glass, proceeds partly from some
ruggedness of the surface: and chiefly from a kind of tarnish, or dirty
smoaky substance, which adheres to the surface of that very hard body; and
though the pointed parts cannot penetrate the substance of Glass, yet may
they find pores enough in the tarnish, or at least make them.

This Structure I somewhat the more diligently survey'd, because I could not
well comprehend, how, if there were such a glutinous matter in those
supposed Sponges, as most (that have observ'd that Object in a
_Microscope_) have hitherto believ'd, how, I say, the Fly could so readily
unglew and loosen its feet: and, because I have not found any other
creature to have a contrivance any ways like it, and chiefly, that we might
not be cast upon unintelligible explications of the _Phaenomena_ of Nature,
at least others then the true ones, where our senses were able to furnish
us with an intelligible, rationall and true one.

Somewhat a like contrivance to this of Flies shall we find in most other
Animals, such as all kinds of Flies and case-wing'd creatures; nay, in a
Flea, an Animal abundantly smaller then this Fl