[ *79 ] 
The Air was partly banilhed from the Infide of 
this Mafs of Glafs : There is none in the liquid red- 
hot Matter of a Glafs Furnace. It was purely out 
of Complaifance for a generally received Opinion, 
that Mr. Mariotte allowed the exterior Fluid any 
Share in the Phenomenon j and Mr. Homherg put 
the finifhing hand to its Exclufion. But the Sort of 
Temper given to the Drop by plunging it red-hot 
into cold Water, and its Comparifon with temper’d 
Steel, is not fo much a Caufe as a Comparifon : 
And moreover, is this Comparifon very juft? Can 
there be any between a long, thin Sword-Blade, 
which breaks into two or three Pieces, and a thick 
inflexible Mafs of Glafs, which flies into Powder. 
The Tail alone of the Drop might feem to favour 
this Parallel : But an Experiment, which I made, 
entirely deftroys this Opinion, and proves, that it 
is not the Spring, or the Vibrations of the Parts 
of the Drop, that occafion its burfting. 
I put about half the Tail of a Glafs Drop into a 
Vice between two Bits of Deal-board of about a 
Finger’s Breadth. I lcrew’d the Vice, till I faw this 
fmall Cylinder or Thread of Glafs make Imprefflons 
in the Wood on each Side for its Lodgment, in or- 
der to be lure that it could not be fufccptible of 
Vibrations. In this Condition I broke the End of 
the Tail, fupporting it on my Nail, to prevent force - 
ing any Part but the End which I intended to break; 
and in order to be the more certain of oivins no 
Shock to the Part that was fqueezed in the Vice. 
My Drop flew into Powder as ufual ; and the Por- 
tion fecured between the two Bits of Wood, per- 
fectly retained its Figure in the Imprdlions wherein 
Z 2 it 
