Three Papers of 'Dr. Martin Lyfter , the firfi of the 
Nature of Earth- quak^s\ more -particularly of the 
Origine of the matter of them^ from the Pyrites 
alone. 
I Have elfewhere ^ fliewn that the breath of the Pyrites 
isS\x\^\ixxvextotaSubJiantia: Alio, That it natural- 
ly takes fire of itfelf: Again, that the material caufe 
of Thunder and Lightning, and of Earthquakes is one 
and the fame; t'/;^. Thelnflamable breath of the Py- 
rites, the difference is, that one is fired in the Air the 
/ other, under ground: Of which laft, thefe (I think) 
are^ulEcient Arguments: A thing burnt with Light- 
ning fmells of very Brimftone ; again, the lubtlety and 
thinnefsof the flame i alfo the manner of its burning, 
which is often obferved to be particulatim or in fmall 
fpots, vapour like. And of Earthquakes, the Sulphure- 
ous ftink of waters fmelt before, and of the very Air it 
felf after them: of which innumerable infl:ances occur 
in the relations of them. 
They alfo agree in the manner of the noife, which is, 
^obe carryed on, as in aTrain fired; the one rowling and 
ratling through the Air , taking fire , as the vapours 
chance to drive; as the other fired under ground in like 
manner moves with defultorie noife, as it fhall chance 
to be continued. 
That the Earth is more or lefs hollow is made proba- 
ble, by what is found evety where in the Mountains , z^/^. 
Natural Cavities or Chambers, which the Miners of the 
North call Self opens. Thefe they meet with very fre- 
quently, fome vaftly great, and others lefs, running 
aDe FontibusMedicati* Anglise. 
away 
