[ 74i ] 
to fconr his Canal, and deepen it ; that they came 
to a white Quickfand, which afforded to ail the 
Neighbourhood excellent Water in Plenty, 
In the gravelly Soil of London , and where the 
two Shocks were felt by us, in the Beginning of 
the Year, we know , there is not an Houfe in the 
whole Extent of this vaft City, and all around it, but 
a Spring of Water is ready, upon digging a Well: 
Whence we have much Rcafon to believe, that the 
internal Parts of the Earth are like a Sponge foak’d in 
Water; fothatthe only dry Part of it isthe Superficies; 
which is the Object, and the Subject, of that electric 
Vibration, wherein (according to my Sentiments) 
an Earthquake confifts. 
This fhews the Miftake of the Antients; who, 
fancying that Earthquakes proceeded from fubterra- 
neous Eruptions, built their prodigious Temple of 
Diana of Ephefus upon a boggy Ground, to pre- 
vent fuch a Difafter. 
6. Earthquakes are truly moft violent in a rocky 
Country ; becaufe the Shock is proportionate to the 
Solidity of the Matter ele&rify'd: So that Rocks, 
old Caftle-Walls, and flrong Buildings, are moft ob- 
noxious to the Concuftion. The Ille of Cerigo was 
more liabie, and more rudely handled by the late 
Earthquake; both becaufe it was an Ifle, and be- 
caufe it was rocky. So we muff fay of the late 
Earthquake in Switzerland , that fplit the Moun- 
tain and the old Caftle-Wall. Whence Mr. John- 
fon , in his fecond Letter, fays, it crack'd a very 
flrong brick Houfe in Gosberton by Spalding. Dr. 
Doddridge obferves, from Northampton , that Dr. 
Stenehoufe s Dwelling, being a very flrong one, 
was 
