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as will refult from the Equilibrium of the Columns, 
and from the Gravitation afting perpendicularly to the 
Surface. Indeed though this Reafon has a Degree of 
Plaufibility, yet there are many who think it to be of 
fmall Force. Perhaps, fay they, the Earth has never 
been in this fluid Condition. 
The fecond Reafon, which I believe will have a 
greater Weight with every Body, is this. Confider- 
ing the Earth as it is at prefent, and without carrying 
our Thoughts fo far back as to its Formation, if the 
Ocean, which is now upon its Surface, has any con- 
fiderable Depth, and if its Parts preferve a Commu- 
nication with each other, from Region to Region, by 
fubterraneous Canals; it can only keep an Equili- 
brium by this Means, becaufe its Superficies is the 
fame as it would have, were the whole a Fluid. 
XXXIV. This fecond Reafon has fuggefted a Re- 
flexion to my Mind, concerning the Equipoife of the 
Columns now calculated, Art. XXXI. and XXXII. 
Let us firft fuppofe, that the Earth is our fluid Sphe- 
roid, compofed of Beds of different Denfities ; and 
that afterwards this Fluid hardens into a Solid, fo that 
the different Beds or Strata , of which it is made up, 
are of no other Ufe but to caufe a Gravity by their 
Attractions. Then let us fuppofe, that the Seas and 
great W aters about the Earth have a Communication 
with each other, by means of fome fubterraneous 
Canals. As the Waters of the Sea, which unite with 
one another, are probably homogeneous, the forego- 
ing Calculation, wherein we have confider d the Sphe- 
roid as a Fluid, can no longer take Place, becaufe we 
have there fuppofed, that the Fluid contain'd in the 
Canal BCN is of a Denfity, that varies from the 
Q^q Centre 
