OF CORNWALL. 29 
or fountain where there was no water before ; the earth is porous 
in all its parts, full of chinks and duds in moft places, and opens 
into wide fubterraneous caverns in others: Water is perpetually 
falling and infmuating itfelf by its own gravitation and fluidity 
into the hollows it meets with, or raifed from lower into higher 
pofitions attracted by falts or fands, or tranfpired in vapour, fo that fink 
as deep as we will, we find water either at reft in natural cavities, 
or circulating from higher into lower chanels, fometimes in large 
currents, oltner in fftiall threads and rills, but in fome fhape or other 
eveiy where coafting through the veins of rock or clay, till it meets 
with fuch reiiftance from the ftrata that it is forc’d out through 
the foil into the open air. This is the general ftate of the earth, 
and to continue this moifture (without which the earth muft foon 
become a diy faplefs cruft) rrefh fupplies are perpetually defeending 
rom rains and dews, and leaking into the earth from lakes, 
morailes, rivers, and brooks ; where the paflages are free and 
op^n, the defeent is quick, and the increale of fprings eaftly to 
be perceived, but where the chink and clefts of the rocky ftrata 
are clofe, or a large horizontal, impenetrable rock interpofes, or 
where the fallen moifture is forced by any other obftacle to take a 
large round before it can Supply any conftant fpring, there prefent 
hidden rain can have no vifible effect. If the duds which colled 
and convey thefe waters to their apertures are long, ferpentine, 
and many, the fpring fhews no want of moifture in times of 
drought, becaufe of the many duds which ferve it, nor any increafe 
a tei heavy rains, becaufe the chanels of its nourifhment are long, 
winding, and require time to reach the fountain head. A^ain, if 
perennial fprings derive their water (as may often be the cafe) from 
large caverns which alfo have their fupplies from rain, by duds of a 
etermined number and certain dimenftons, which are neither con- 
tiaded nor dilated, then will the ftream be one certain equable 
quantity let the feafon be ever fo wet and rainy. If the feafon be 
ex reme ) ry thefe caverns are capable of fupplying the perennial 
pi mgs to wifeh they give rife, till frefti fupplies from rain, or dew, 
or o b arrive which muft generally be the cafe before the caverns 
are ex au ie . From this fhort view of the internal ftrudure of 
t e eart , it appears that there is nothing furpriftngin fprings being 
perennial, they aie nothing more than a colledion of little rills of 
Water , ( as r * Vcrs aie a colledion of brooks) which tending nearly 
one way aie united at laft, and break out into open air, and though 
ey owe not their immediate rife to the waters of the Atmofphere, 
as e temporary occaftonal fprings do, yet proceed from duds and 
re ervoirs ed by the moifture of the adjacent ftrata, which moifture 
primal i y pioceeds from fnow, hail, dews, and rain, though more 
I flowly 
