OF CORNWALL. 27 
portionably rais’d, as they were deeper, to the fixth Thermometer, 
which, being two feet under-ground, the Spirit was ten degrees 
above the freezing point.” Veget. Stat. p. 348. Now what are 
we to afcribe thefe different degrees of warmth unto ? To fubter- 
raneous fires, operating fo uniformly within two feet of the furface? 
No, certainly ; but to the coldnefs of the air above, and to the 
mere equal temperature of the earth beneath, into which the cold of 
the air pierces lefs and lefs, in proportion to its diffance from the 
furface, till at laft the variations of the air have no effect at all. 
The truth is, fire is diftributed in every part of our globe ; and in 
the bowels of the earth, it is not fubjeft to the checks and refifiance 
of cold, fo much as it is near the furface ; hence arifes a fenfible 
difference ; and it is warmer where this fire has liberty to a<H, than 
where it is controuled and repelled by frefh and cold air. But this 
fuperiour heat below cannot be a caufe of fufficient power to produce 
the effect now in queftion ; I mean, the Origin of Springs : this 
univerfal fire, whilft it remains difperfed in that harmlefs equilibrium 
to which Providence has gracioufly deftined it, is weak and feeble, * 
and its power to evaporate Water, even under-ground, muff be 
too fmall and inconfiderable to give rife to all conftant Springs. If 
there were fuch a fubterraneous central fire as fome learned men' 
have fancy’d, conffantly exerting itfelf, and a&ing with a force gra- 
dually greater as it is nearer to the centre of the earth, this would 
be a cauie Sufficient, and equal to the effect ; but that there is any 
fuch fire does by no means appear ; neither is it conceivable that 
any fuch fire san flibfiff without preying upon, and perpetually corr- 
fuming, the vitals cf the earth. If there was any fuch fire, the 
deeper we defeend in mines the hotter we fhould feel it, the heat 
mcreafing by equal degrees the nearer we approach the fuppofed 
region of fire % but no fuch regular increafe was found by the fedu- 
lous experiment: of Morton. In the fecond experiment u , Feb. 1 6, 
at 9, a. m. the 1 nermometer Handing low, viz. at five degrees 
below hard frcH in the open air, when fufpended for the fpace of 
one hour in a Well, at the depth of 25 feet, it rofe 14 degrees. 
Feb. 27, 9 a * ni. Handing at two degrees below bard froH in the 
air, when fufpended at the depth of forty feet, it rofe ten degrees 
in lefs than half an hour; and Feb. 24, 1703, (See the ninth Ex- 
periment) Handing at half a degree below hard froH, it rofe fixteen 
degiees in a quarter of an hour, when fufpended at forty feet ; and 
w hen at hard froH, December 13, 1704, it rofe fixteen degrees in 
a quarter of an hour, when fufpended at twenty-three feet two 
inches (Experiment XII.) : hence it appears, that when the fpirit 
page 120. 
1 Woodward Nat. Hilt. 
“ lb. p. 300. 
was 
