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and Eruption?. I know there are many Grange 
Relations of Effe&s of fubterraneous Fires, told by 
Authors that deal pretty much in the Marvellous, 
and whofe Minds were prepoflefled with thofe vul- 
gar Notions. My Conceptions of the Matter are 
deriv’d from the more general Appearances, and 
what we have leen and felt ourfclves. 
After we have treated this Argument in a fuper- 
ficialView, we muft go a little deeper. If we would 
confidcr things like Philofophers, let us propofe to 
ourfelves this Problem j 
JVLere is the Tower to be plac’d that is requir’d 
to move a Surface of Earth 30 Miles in E)ia- 
meter ? 
To anfwer this, confult the Engineers, and thofe 
that make Mines in the Sieges of Towns. They 
will acquaint us, that the EfFetfl of Mines is pro- 
duc’d in Form of an inverted Cone: And that a 
Diameter of 30 Miles in Bafe, will require an Axis 
of 1 y or 20 Miles to operate upon that Bafe, lb as 
to (hake it, at lead. So that the Vapours, and what- 
ever Power we propofe to operate upon that Bafe, 
according to the foregoing Hypothcfis, in order to 
form the Appearance of an Earthquake, mud be 1 y 
or 20 Miles deep in the Earth. 
But what Mind can conceive, that any natural 
Power is able to move an inverted Cone of folid 
Earth, whofe Bafe is 30 Miles in Diameter, and 
Axis 20? Or, was it poilible, would not the whole 
Texture of that Body be quite didurbM and fhat- 
ter’d } efpecially in regard to its Springs and Foun- 
tains ? But nothing like this is ever found to be the 
Confcquence of an Earthquake, tho' fatal to Cities. 
Apply 
