ANNIVERSAlir ADDEESS OF THE PRESIDENT. 



Ixxxiii 



It is scarcely needful to remind the Fellows of this Society that 

 we are in possession of valuable tables of subterranean tempera- 

 tures observed in the mines of Cornwall by our associates Mr. E. 

 "W. Fox and Mr. W. J. Henwood, and that these gentlemen, with other 

 careful observers of the same class of phenomena, have taken their 

 measurements either from the water issuing from unbroken portions 

 of the rock, or from the rock itself, as tested by a thermometer 

 buried in a bore-hole for at least some hours. The air of the exca- 

 vations is necessarily apt to be affected by the causes above referred 

 to, as well as by the heat generated by the men, candles, &c. ; but 

 even observations on the air, besides being interesting with refer- 

 ence to the condition of the work-people, exhibit clearly enough the 

 remarkable progression of temperature in depth, as well as another 

 fact destined to be very important in the working of our deep mines, 

 viz. the gradual effect of the ventilating currents in cooling the sur- 

 faces of rock which affect the air. Amid the other objects of my 

 frequent underground journeys, I have often been led to note, with 

 some care, the observed temperature of particular points at succes- 

 sive depths, and, in many cases, in successive years ; and the fol- 

 lowing extracts may interest some of our Members by aiding in the 

 confirmation of the above two propositions. 



I therefore venture to give the following tables, as showing the 

 temperature of the air in several of our deepest mines, which have 

 unfortunately within these last few years been abandoned to the 

 waters : — 



Depth. 



Holmbush Copper-mine, CaUington, Cornwall. 



In 

 fathoms. 



In 

 feet. 



16th Oct. 1857. 



2nd Sept. 1861. 



100 

 124 



132 



160 

 175 



600 

 744 



792 



960 

 1050 



Surface — 

 At 10.30 A.M 66°'5 



66° 



Inclined shaft... 72 



In inclined shaft 76 



East end 84 



Do. in rise 88 



At Wall's, western end... 79 



Water atdo 77 



South cross cut 78 



End of level, west 83 



Pitch in the lead lode... 84 



West end 84 





Do. at shaft 82 



West end 86 





