Prominences. The drop it self, before it be broken, appears very
transparent, and towards the middle of it, to be very full of small
Bubbles, of some kind of aerial substance, which by the refraction of the
outward surface appear much bigger then really they are, and this may be in
good part removed, by putting the drop under the surface of clear Water,
for by that means most part of the refraction of the convex Surface of the
drop is destroyed, and the bubbles will appear much smaller. And this, by
the by, minds me of the appearing magnitude of the _aperture_ of the
_iris_, or _pupil_ of the eye, which though it appear, and be therefore
judged very large, is yet not above a quarter of the bigness it appears of,
by the _lenticular_ refraction of the _Cornea_.

The cause of all which _Phænomena_ I imagine to be no other then this, That
the Parts of the Glass being by the excessive heat of the fire kept off and
separated one from another, and thereby put into a kind of sluggish fluid
consistence, are suffered to drop off with that heat or agitation remaining
in them, into cold Water; by which means the outsides of the drop are
presently cool'd and _crusted_, and are thereby made of a loose texture,
because the parts of it have not time to settle themselves leisurely
together, and so to lie very close together: And the innermost parts of the
drop, retaining still much of their former heat and agitations, remain of a
loose texture also, and, according as the cold strikes inwards from the
bottom and sides, are quenched, as it were, and made rigid in that very
posture wherein the cold finds them. For the parts of the _crust_ being
already hardened, will not suffer the parts to shrink any more from the
outward Surface inward; and though it shrink a little by reason of the
small parcels of some Aerial substances dispersed through the matter of the
Glass, yet that is not neer so much as it appears (as I just now hinted;)
nor if it were, would it be sufficient for to consolidate and condense the
body of Glass into a _tuff_ and close _texture_, after it had been so