MicROGRAPHIiA, 
Flame 5 fomething there is afcribable to. the Heat , for that it miay rarifie — 
the more.vplatil and {pirituous parts of thofe combuftible Liquors, and 
being madelighter thenthe Air, it may be protruded upwards by that 
more ponderous fluid body in the Form of Vapours; but:.this can be 
afcribed to the afcenfion of but a very little,and moft likely of | that on 
ly which afcends without the Week. As for the Rifing of it ina Spunge, 
Bread,Cotton,@c, abovesthe faperficies of the fubjacent Liquors, what 
has been faid about the Filtre (if confidered ) will ealily fuggeft a 
reafow , confidering that all thefe bodies abound with fall holes ot 
From this fame Principle alfo ( wiz. the unequal preffure of the Air a4 
gaint theunequal fuperficies of the mater.) proceeds the caute of the ac* 
‘ .ceflion or incurfion of any floating body againftthe fides of the con* 
taining Veflel, or the ¢ppropinquation of two floating bodies, as Bubbles, 
Corks, Sticks, Straws, &c, one towards another. » As for inftance, Take 
a Glafs-jar, fuchas AB in the feventh Figvre, and filling it pretty near the 
tup with water , throw) into it a {mall round piece of Cork, as€,and: 
plungeit all over in water, thatitbe wet , fo as that the water may rife 
up by the fides of it,then placing it any where uponthe fuperficies, about 
an inch,or one inchand a quarter from any fide, atid you fhall perceive it 
by degrees to make perpexdicularly toward the neareft part of the fide, 
and the nearer it approaches, the fafter to be moved; the reafon of 
which Phenomenon will be found no other then this, that the Air has a 
reater preflure againft the middle of the faperficies, themit hasiagainft 
ike parts that approach nearer, and. are comtiguows to the fides.» Now 
that the prefiure 1s greater, may (as lfhewed before in the explication 
of the third Figure ) be evinced from the flatting of the water in the 
middle, which arifes from the gravity of the under fluid: for fihce,as k 
thewed before.if there were no gravity inthe under ftid,or that it were 
equal tathat of the upper , the termmating Surface would be spherical, 
and. fince it isthe additional preffure of the gravity of water that makes 
it fo flat, it follows; that the preflureupon the middle mult begréater'then 
towards the fides. Hence the Balb having a ftronger prefiure againft that 
fide of it which refpects the middle of the fuperficies, themagainft that 
which refpects the approximate lide , muft neceflarily move towards that 
part, from whence it finds leaft refiftance, and fo be accelerated; asthe re- 
fiftance deécreafes. Hence the more the water israifed under thap part 
of its way itis paffing above the middle, the-fafter io is moved : And 
therefore you will find it to move fafter:inE thet in D, and inDthen 
_ inC. Netthercould: Ifind the floating fubftance tobe moved av all, un- 
tilit! were placed upon fome part'of the Saperficres that was: fentably: ele+ 
_ yated abovethe height of the middlepart.. Now:thanthis may be the 
true caufe, you may try with a blown Bladder, and.an exactly ronrid Ball 
upon a very {mooth fide of fome pliable body', as Horz or Quicksiloer. 
29° 
For if theBall-be placed under a‘part of the Bladder whidliis iponone 
fide of the middle of its preflure.,. and you pre{s ftrongly again{t the 
Bladder,you fhall find the Ball moved.from the i calla fides; 
N23 aving 
/ 
