[ 247 ] 
I find, by infpe&ing Mr. George Martins Col- 
lection, and Comparifon of the Scales and Degrees 
of Heat with various Thermometers, that the Tem- 
perature of Heat in thefe Caverns coincides with 
that in the Cave at the Obfervatory at \ 'Paris , 
within one Degree; which I think comes very near, 
confidering the Obfervations were made with dif- 
ferent inftruments, and formed upon different Prin- 
ciples. 
At the Foot of a high Hill, adjacent to thefe Vaults, 
i flues out a curious Spring, whofe Water I found 
exactly of the fame Temperature with that under- 
ground $ though, when the Thermometer was ex- 
poled to the open Air, it flood at 57 0 . 
Permit me, Sir, to fubferibe myfelf, with the ut- 
mofl Truth and RefpeCt, 
London , March I 5. 
1 747-8. Tour moft obedient 
humble Servant , 
Henry Baker. 
A terrible Thunder-Storm, 'June 12, 1748, fhook the Earth 
to fuch a Degree as to throw down thofe Chalk-Vaults. 
XVII. 
