1823.J" Mr. Moi/te onthe Ternperahireof Mines, 15 



direction of the wind, and change at the same end as the wind 

 passes from one into the other of the two quarters in front of th€i 

 pier. This alternation in the direction of the surf makes it difii-- 

 cult to adjust the direction of the enclosing piers so as to prei 

 vent the strong surf in any gale from passing along such piers to* 

 and accumulating at, the entrances. 



I am, Sir, your very humble servant, 



John B. Loj^gmike. 



( To be continued.) 



Article III. 



On the Temperature of Mines. By M. P. Moyle, Esq. 



(To the Editor of the Annals of Philosophy.) 



DEAR SIR, Helston, Mmj 1 1, 1823. 



Nearly twelvemonths have now elapsed since the tempera- 

 ture of many parts of Huel Abraham, Crenver, and Oatfield 

 Copper Mines, in this county, were taken, an account of which 

 you did me the favour to publish in the Annals for January last. 

 Many of the experiments were a few days since repeated in pre- 

 cisely the same spot, and under similar circumstances, as before, 

 and nearly with the same results, excepting the temperature of 

 the water accumulated at the bottom of Oatfield engine shaft 

 below the depth of 182 fathoms from the surface, in consequence 

 of the pumps being drawn up from below that level. 



The coldest part of this water, ten months ago, at the depth 

 of 1,164 feet from the surface, and in 12 fathoms of water, was 

 6&^. Last week, at precisely the same depth, it was only 59°; 

 while the water at the surface of this shaft was 77°. This 

 increase of temperature at the surface is to be attributed to the 

 immense quantity of warm water sent from distant parts of the 

 other mines to this shaft to be drawn out ; and although it falls 

 several feet into this shaft, which keeps the water in a constant 

 and great agitation, yet it does not effect the temperature at the 

 above-mentioned depth so much as might be expected. 



I regret much that the registering thermometer could not be 

 sunk to a much greater depth, and quite out of the influence of 

 the falling waters, as I am inclined to think that it must ere this 

 have arrived, or nearly so, to the mean annual temperature, or 

 53°. 



I have before shown that by admitting the gradual increase of 

 temperature (according to our descent) after a certain ratio, the 

 temperature of this depth ought to be, at the lowest calculation, 

 70°. How comes it then to be less by 11" and 18° minus since 

 this place was in the full course of working ? 



