( 9P<^ ) 
Atoms might in length of time coalefce and tiih * firtuU 
toujlj together, as we fee Saks fiicor in Water; and gradu- 
-ally concrading thcmfelves into a narrower compafs, might 
lie like a Train of Gunpowder in the Ether, till catching 
fire by feme internal Ferment, as we find the Damps in 
Mines frequently do, the Flame w’ould be communica* 
ted to its continued parts, and To run on like a Train fir’d. 
This may explain how it came to move with fo uncon- 
ceivable a Velocity; for if a continu’d Train of Powder 
were no bigger than a Barrel, it is not eafy to fay how 
very faft the fire would fly alongft it, much lefs can wc 
imagin the Rapidity of the Accenfion of thefe more in* 
flammable Vapours, lying in a Train of fo vaft a Thick- 
nels. If this were the C ale, as it is highly probable, it was 
not a Globe of Fire that ran along, but a fuccelfive kin- 
dling of new: Matter : and as fome parts of the Earth might 
emit thefo Vapours more copioufly than others, this Train 
might in fome parts thereof, be much denfer and bigger 
than in others, w'hich might occafion feveral fmaller Ex- 
plofions, as the Fire ran along it^ befides the great ones 
-which were like the blowing up of Magazines. Thus we 
may account for the rattling Noife like fmall- Arms, heard 
after the great Bounce on the Explofion over Tiverton ; 
the Continuance of which for fome time, argues that the 
Sound thereof came from Diflances that encreafed. 
What may be faid to the Propagation of the Sound thro* 
Vi Medium, according to the receiv’d Theory of the Air 
above 300000 times rarer than what we breath, and as I 
faid before, next to a Vacuum, I mufl confefs 1 know not. 
Hitherto we have concluded the Air to be the Vehicle of 
Sound ; and in our artificial Vacuum we find it greatly 
diminifh’d t but we have this only Inftance of theefletS 
of an Explofion of a Mile or two diameter, theimmenfi- 
ty of which may perhaps compenfate the extream Finc- 
nefs of the Medium, 
F I N 7 S. 
* Dele fjrtuitoujt/. 
