'liG Summarij Reviexc of the late. Investigations 



the li° of temperature, which, according to my previous ad- 

 missions, ought to arise from the increased length of the at- 

 mospheric column ; but I apprehend that some part of this 

 nuist be allowed for the loss of temperature in the process of 

 raising the water to the adit-level." 



" I ought to apologize to the Society for submitting to its 

 notice calculations so vague, and perhaps gratuitous, as the 

 above. My i-easons for doing so are, my anxiety to induce 

 others to submit the subjects of my rude conjectures to the 

 test of experiment, and my desire to have some tangible quan- 

 tity to base my future reasonings on. Some of my calculations 

 may be found erroneous ; but I am convinced that, however 

 erroneous, they aiFord ample proof of the inadequacy of all the 

 artificial and extraneous sources of heat in mines, to account 

 for the temperature indicated in them by the thermometer. 

 Hence it follows, that the natural temperature of the earth in 

 the mines of Cornwall, at the depths mentioned, must be very' 

 considerably above that of the mean of the climate. This' 

 conclusion is equally deducible from many facts which have 

 been observed in mines. The most conclusive of these, is the 

 high temperature of extensive collections of water in aban- 

 doned mines, or in parts of mines that have been long aban- 

 doned. In many cases of this kind it is impossible to believe 

 that the temperature can have been derived from any other 

 source than the rocky walls of the cavity in which it is con- 

 tained ; and as these walls could not derive their temperature 

 from any foreign source, the conclusion is equally in favour 

 of the natural high temperature of the body of the eartli 

 at certain depths. An example of this kind is given in the 

 account of Botallack mine, where the temperature of a large 

 isolated collection of water is stated to be 62° at a depth of 

 about 400 feet from the surface." 



" A still stronger instance, perhaps, in supjiort of tlie same 

 conclusion, is aflfbrded by the details of the other submarine 

 mine. Little Bounds. This mine was formerly wo]'ked to tlie 

 depth of 500 feet. Of late years very little has been done, and 

 the water has risen to within forty fathoms of the adit, where 

 it is kept stationary by the partial operation of the pumps. 

 There is thus a permanent body of water extending from the 

 depth of 300, to thrt of 500 feet below the surface, and to per- 

 haps half that distance horizontally. This water, as discharged 

 by the pumps (in 1822), is of the temperature of 56P. It is 

 needless to remark that the daily jiresence of half a dozen men, 

 and the daily consumption of a couple of pounds of candles, 

 and as many of gimiiowtler, could have no perceptible efFect 

 in augmenting the temperuture of the vast body ol' water that 



inundated 



