932 
MicroGRAPHIA. 
which and your eye, the rifing fmoak of fome Chimney is interpos'd ; 
which brings into my mind what I had once the opportunity to obferve, 
which was, the Sun rifing tomy eye juft over a Chimney that fent forth 
a copious {team of fmoak ; and taking a fhort Te/e/cope, which Ihad then 
by me, I obferv'd the body of the Sun, though it was but juft peep'd 
above the Horizon, to have its underfide, not onely flatted, and prels‘d 
inward, as it ufually is when neer the Earth; but to appear more pro~ | 
tuberant downwards then if it had fuffered no refraction at all; and 
befides all this; the whole bod y of the Sun appear’d to tremble or dance, 
and the edges or limb to be very ragged or indented, undulating or wa- 
ving, much in the manner of a flag in the Wind. ! 
This I have likewife often obferv’d in a hot Sunthiny Summer’s day, 
that looking on an Objeét over a hot ftone,or dry hot earth,I have found 
the Object to be undulated or fhaken, much after the fame manner, And 
if you look upon any remote Object through aTelefeope (ina hot Sum- 
mer's day efpecially ) you fhall find it likewife toa ppear tremulous. And - 
further, if there chance.to blow any wind, or that the air between you 
and the Obje@ be in a motion or current, whereby the parts of it, both 
rarify'd and condens'd, are fwiftly remov’d towards the right or left, if 
then you obferve the Horizontal ridge of a Hill far diftant,through a very 
_ good Telefcope, you fhall find it to wave much like the Sea, and thofe . 
waves will appear to pafs the fame way with the wind. ~ 3 
_ From which,and many other Experiments, ‘tis cleer that the lower Re- 
gion of the Air,efpecially that part of it which lieth neereft to the Earth, 
has, for the moft part, its conftituent parcels varioutly agitated, cither by 
heat or winds, by the firft of which, fome of them are made more rare, 
and fo fuffer a lefs refraction ; others are interwoven, either with afcend- 
ing or defcending vapours 3 the former of which being more light, and 
fo more rarify’d,have likewife a lefs refraction ; the Jatter being more hea- 
vie, and confequently more denfe,have agreater. = 
Now, becaufethat heat and’ cold are equally diffus'd every way 3 and 
that the further it is fpread, the weaker it grows$ hence it will follOar 
that the moft part of the under Region of the Air will be made up of fe- 
veral kinds of /ewtes, fome whereof will have the properties of Convex, 
others of Coxcave glafes,; which, that! may the more intelligibly make 
out, we will fuppofe in the eighth Figure of the 37. Scheme, that A te- 
prefents an afcending vapour, which, by reafor of its being fomewhat 
_ Heterogeneous to the ambient Air,is thereby thruft into a kind of Globular 
, hot any where terminated, but gradually finifhed, that is, itis moft 
rarity'd in the middle about A, fomewhat more condens’d about B B, 
more then that about CC; yet further,about D D, almoft of the fame 
denfity with the ambient Air aboutEE; and laftly, inclofed with the 
more denfe Air F F, fo that from A, to. FF, there is a contintial nm 
creafe of denfity. The reafon of which will be manifeft, if we confider the. 
rifing vapour to be much warmerthen the ambient heavie Air; for by 
“the coldne& of the ambient Air, the thell EE will be mote retrigerated 
then D D,and that then C C,which will be yet more thenB B, and that 
more 
