f
the Object; for I think, that there are very few will grant, that Glass, by
as gentle a heat as may be endur'd by ones hand, should send forth any of
its parts in steams or vapours, which does not seem to be much wasted by
that violent fire of the green Glass-house; but, if yet it be doubted, let
Experiment be further made with that body that is accounted, by Chymists
and others, the most ponderous and fix'd in the world; for by heating of a
piece of Gold, and proceeding in the same manner, you may find the same
effects.

This trembling and shaking of the Rays, is more sensibly caus'd by an
actual flame, or quick fire, or anything else heated glowing hot; as by a
Candle, live Coal, red-hot Iron, or a piece of Silver, and the like: the
same also appears very conspicuous, if you look at an Object betwixt which
and your eye, the rising smoak of some Chimney is interpos'd; which brings
into my mind what I had once the opportunity to observe, which was, the Sun
rising to my eye just over a Chimney that sent forth a copious steam of
smoak; and taking a short _Telescope_, which I had then by me, I observ'd
the body of the Sun, though it was but just peep'd above the Horizon, to
have its underside, not onely flatted, and press'd inward, as it usually is
when neer the Earth; but to appear more protuberant downwards then if it
had suffered no refraction at all; and besides all this, the whole body of
the Sun appear'd to tremble or dance, and the edges or limb to be very
ragged or indented, undulating or waving, much in the manner of a flag in
the Wind.

This I have likewise often observ'd in a hot Sunshiny Summer's day, that
looking on an Object over a hot stone, or dry hot earth, I have found the
Object to be undulated or shaken, much after the same manner. And if you
look upon any remote Object through a _Telescope_ (in a hot Summer's day
especially) you shall find it likewise to appear tremulous. And further, if
there chance to blow any wind, or that the air between you and the Object
be in a motion or current, whereby the parts of it, both rarify'd and
condens'd, are swiftly remov'd towards the right or left, if then you
observe the Horizontal ridge of a Hill far distant, through a very good
_Telescope_, you shall find it to wave much like the Sea, and those waves
will appear to pass the same way with the wind.

From which, and many other Experiments, 'tis cleer that the lower Region of
the Air, especially that part of it