Mr, more’s Account of , &c. r i 
<c the reverberation of the blaft from the Tweer *, been drawn 
out whi lft fluid into long cobweb-like threads (Sometimes 
44 ten or twelve feet in length) and affixed itfelf to the beams, 
44 &c. of the bellows room.” 
Whoever has attentively viewed the lame furnaces wherein 
iron ore is fmelted by coak, will readily allow, that they preftnt 
the moft ftriking refemblance (however diminifhed) of that mold 
tremendous of all appearances, the eruption of a volcano ; and 
that the moft exadt pictures hitherto leen of the flowing of the 
lava from the one is fhewn bv the running of the flag- from the 
other : this has induced me to lay before you, for the infpedtion 
of the Royal Society if you judge it worthy their attention, 
l'ome of the fcoria in its capillary Rate, and with all due de- 
ference to the acknowledged abilities of Sir william Hamil- 
ton, to fubmit to your confi deration, and that of the learned 
Body over which you fo defervedly preflde, whether the fine 
filaments may not be produced in the eruption of the great 
furnaces of nature, by means fimilar to thole by which we lee 
them formed in the furnaces of art. Sir william feems to 
think, “ That (what he calls) the natural fpun glafs which 
44 fell at Ottaiano, as well as that which fell in the life of 
44 Bourbon in 1766, muff have been formed, moft probably, 
44 by the operation of fuch a fort of lava as has been juft de- 
44 ficribed (that is, perfectly vitrified) cracking, and feparating 
44 in the air at the time of its emillion from the volcanos, and 
44 by that means fpinning out the pure vitrified matter from 
44 its pores or cells, the wind at the fame time carrying off thofe 
44 filaments of glafs as fall as they were produced.” See 
p. Si. 
* The Tweer is thnt opening through which the air is driven by the bellows 
into the body of the furnace. 
II 2 
That 
