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that of the sun, and who have felt the scorching heat which it 
radiates, will form a high conception of the intense temperature 
of the same lava at the bottom of a vertical column several miles 
high, and communicating with a great reservoir of fused matter, 
which if it were to begin at once to cool down, and were never to 
receive further accession of heat might require a whole geological 
period before it solidified.” Asa proof of that eminent geolo- 
gist’s extensive knowledge of thermal springs, it is remarkable 
how close he comes in his ideal description of those at Bath 
to the opinion we are now able to form by local discoveries, and 
by the advanced stage geological science has reached during the 
thirty years which has elapsed since that address was delivered. 
Throughout the address Sir Charles is much more in favour of 
volcanic influence as the impregnating power, rather than the 
normal high temperature of the earth’s crust at a great depth ; 
notwithstanding, as he says, ‘‘ we are at so great a distance as 490 
or 440 miles from the nearest region of active or recently extinct 
volcanoes.” 
The vast volume of the water moving slowly through rocks at 
adepth of nearly two miles, those rocks too having undergone 
such changes through close contact with internal heat at the very 
seat of its original activity, we cannot imagine that that heat has, 
or ever will, subside to the normal temperature of the crust 
of the earth; owing to this we may fairly estimate the heat 
of the water as it leaves the limestone formation to be not 
below the boiling point. If we are wrong in our estimation of 
the heat from that source, the theory of the normal temperature 
of the earth will give similar results, allowing, the depth from 
which the water rises to be as we have stated 10,000 feet, Sir 
Charles Lyell gives the ratio as proved in deep coal pits in the 
North of England to be 1° in 65 to 70 feet. Allowing the mean 
temperature at the surface to be 45°F our hot springs should be 
207°F. Professor Prestwich found in very deep wells, the water 
to rise in temperature 1°F in 50 to 60 feet after this ratio the 
