r i jo Mr. Six’s "Experiments 
tower ; but under fimilar circumftances I have face feen the 
lame. 
The- following experiments relate to the variation of local 
heat in the earth iti'eif; the diverfity of which appears from 
the different heat of the water iffuing from it at different 
places *. It has been conjectured, that the diverfity of the 
temperature of fprings may probably depend on their different 
elevations in the earth, with refpeCt to the level of the fea. 
Two remarkably deep wells, both near the fea- (here, and 
not .far diftaut from Canterbury, gave me a favourable oppor- 
tunity of making experimental inquiry into this matter; efpe- 
cially as the fituation of the two fprings differed considerably 
from each other in refpedt to the level of the fea. One of 
thefe is a well in Dover Caftle, which is funk 360 feet through 
the high cliff of chalk on which the Caftle Stands, and the 
depth of the well is nearly equal to the height of the cliff 
from the fea. The other is King’s-Well at Sheernefs f , 
which was funk 330 feet through almoft one entire Stratum 
of firm clay, where the fur face of the ground is only four feet 
above high water. 
Supposing therefore the fpring in Dover well to lie level 
with the fea, the fpring of the well at Sheernefs lies 326 feet 
below it ; a circumftance extremely favourable to my experi- 
* The temperature here meant is not that of the very hot fprings which proceed 
from particular local caufes, fometimes rifing near the furface of the earth ; nor 
of fprings which are near enough to the furface of the earth to be affedted by the 
change of temperature in the atmofphere ; but that heat which being found at a 
great depth is more likely to be permanent, and may be fuppofed to originate from 
•fome general caufe in the earth. 
+ See an account of finking this curious well by Sir Thomas Page, Phil. 
Tranf. Vol. LXXIV. p. 6. 
ment. 
