66 Mr Fox on Springs of Water. 
tended to other works of a similar kind, and to bridge-building, and must, 
undoubtedly, become yet more generally extended to these and other 
engineering works, we think Mr Wightman has rendered an important 
service to the useful arts, and deserving, thereby, the particular consi- 
* deration of the Society. The model is a very neat and complete appa- 
ratus ; and we would recommend the drawings and description to be 
printed, to which Mr Wightman will probably add a more detailed 
drawing of the machinery. 
(Signed) Gro. BucHANAN, Convener. 
JAMES SLIGHT. 
Wm. GLOVER. 
Abstract of a Paper relative to Springs of Water. By 
RoBERT WERE FoOx.* 
Mr Fox began by referring to an interesting lecture recently read 
before the Royal Polytechnic Society, in the course of which it was 
suggested that springs of water, especially such as are sometimes 
found on the highest ground of any locality, might be caused by the 
pressure of vapour, generated by the heat existing at great depths 
in the earth. 
If it be assumed, he said, that the subterranean temperature in- 
creases at the rate of 1° Fahrenheit for every 48 feet of depth, 
which he considers to be too high a calculation, and taking the mean 
of this climate at 50° ; this rate will give: 160° at 1 mile deep, 270° at 
2 miles, 380° at 3 miles, 490° at 4 miles, 930° at 8 miles, and 
1370° at 12 miles. 
The heat of boiling water occurring at about 13 mile deep; that 
producing an expansive force of 2.9 atmospheres at 2 miles; of 50 
atmospheres at rather more than 4 miles deep; and Le Roche cal- 
culates that the pressure of vapour in contact with water, would ex- . 
ceed 4000 atmospheres at the temperature of 1386° Fahrenheit, and 
then be nearly equal to the density of water. 
The pressure of a column of water at 60° would, at the rate of 
34 feet to an atmosphere, equal 
155.34 atmospheres at 1 mile deep, 
310.68 tes at 2 miles deep. 
466.00 wee at3 we 
621.36 oa ath ane 
1242.72 ss BEB cn ane 
1864.00 - ab 12 
* Read before the Royal Polytechnic Society of Cornwall, on the 7th No- 
vember 1843. 
