42 
MrcroGRAPHIA 
ded in thole bubbles, by the lofing of theiragitation, by thedecreafe of the 
Heat,lo alfo moft part of their Springand Expanfive powersit follows (the 
withdrawing of the heat being very fudden) that the parts muft-be left ina 
very loofe Texture, and by reafon of the implication of the parts abe about 
another, which from their {luggifhnes and glutinoufne(s I fuppofe to be much 
after the manner of thé {ticks in a Thorn-bufh,or a Lock of WoolsIt will. fol- 
low, I fay, that the parts will hold eachother very ftrongly together,andin- — 
deavour to'draw each other neerer together, and confequently their Tex- 
ture muft be very hardiand {tiff, but‘very much rarified. ) > 901. 09 
~ And this will make probable my next Pofition, ‘That the partmof the Glafs 
are under a kind of tenfion or flexure,out of which they indeavour to extricate and 
free themfélves,and thereby all the parts draw towards the Center.or middle, _ 
‘and would) if the outward parts would give way, as'they do whenthe out- — 
ward ate leifurely’ (as in baking of Glafles)) contract the bulk of the | 
drop into'a much lef$ compafs. For fince,as I proved before,the Internal parts _ 
of the drop, when fluidjwere of a very rarified Texture.and,as it were,tosd 
open like a Lock of Wool,and if they were fuffered leifurely to cool, would — 
be again preft, as it were,clofe together: And fince that the heat;which kept _ 
them bended and open; isremoved , and yet the parts not fuffered to get as 
ineer together asthey naturally would It follows,that the Particles remain 
under a kind of texfiow and flexure , and confequently have an indeavour to — 
free themfelves from that bending and diftenfion, which they do, asfoon as — 
either the tip bebroken, or as foon as by a leifurely heating and cooling, — 
the parts are nealed into another pofture. A393 ee 7 
And this will make my next Pofition probable,that the parts of theGlafs drops 
are contignated together in the form of an Arch,and cannot any where yield or _ 
be drawn inwards.till by the removing of fome one part of it(as it happensin — 
the removing one of the {tones of an Arch)the whole Fabrick is fhatter dand 
falls to pieces,and each oe is left at liberty,fuddenly to extricate it — 
felf: for finceI have made it probable,that the internal parts of the Glafs have — 
a contractive power inwards, and the external parts are incapable of fucha — 
Contraction,and the figure of it being {phericalsit follows,that the fuperficial ~ 
parts muft bear againft eachother , and keep one another from being con* 
dens‘d into a lefs room, in the fame manner as the {tones of an Arch conduce — 
to the upholding each other in that Figure.And this is made more probable _ 
by another Experiment which was communicated to me by an excellent Per- _ 
fon,whofe extraordinary Abilities in all kind of Knowledg, efpecially in that 
of Natural things,and his generous Difpofition in communicating,incouraged 
me to have recourfe to him on many occafions. The Experiment was this: 
Small Glafs-balls ( about the bignefs of that reprefented in the Figure &.) 
would,upon rubbing or fcratching the inward Surface, fly all infander, with 
a pretty brisk noife ; whereas neither before nor after the inner Surface had 
been thus{cratcht, did there appear any flaw or crack. And putting the pie- 
cesof one of thofe broken ones together. again, the flaws appeared much 
after the manner of the black lines on the Figure, @: Thefe Balls were {mall, 
but exceeding thick bubbles of Glafs ; which being crack’d off fromthe 
Puxtilion whillt very hot, and{fo fuffered to cool without nealing them in 
| 7 the 
