ANNIVEKSARY ADDRESS OF THE PRESIDENT. 



Ixxxi 



at Dukinfielfl, by Mr. Fairbairn*, and whence he calcnlatcd that 

 from 231 yaids to 685 yards deep, or 693 feet to 2055 feet, the 

 bottom of the shaft, the increase was such as to give one degree 

 F. for 76-8 feet. At this rate, the temperature of boiling water 

 will be reached at the depth of 2| miles from the surface, whilst by 

 the French experiment it would occur at about 1| mile. 



The coal-miners of Belgium, in the exploration of their narrow 

 and highly contorted coal-field, have, within the last few years, 

 sunk some of their pits, especially in the neighbourhood of Charleroi, 

 to depths which, in several instances, exceed the workings of any 

 other part of the world. 



I am indebted to the kindness of M. Jules Gernaert, the efficient 

 Inspector-in- Chief under the Belgian Government, for observations 

 recently made in some of these collieries. The recorded temperatures, 

 it will be seen, are those of the air in various portions of the exca- 

 vations ; and some allowance may therefore be made in those parts 

 where the warmth is increased by the presence of men ; whilst the 

 down-draught of the ventilating current will be observed to cool, in 

 a great degree, the neighbourhood of the pit. 



Colliery of Q-rand Maaibourg, at Montigny. 



Temperature. 



Cent. 



Fahr. 



Fit Resolu. — Temperature at surface, Dec. 6, 1867 



At the depth of 665 metres, 2180 feet 



0°-2 

 10-00 

 11 -00 

 15 -00 

 20-00 

 23-00 



22-50 



50° 



51-8 



59 



68 



73-4 



72-5 



At the end of 40 metres of stone drift . ... 



In a level 150 metres lonff, in the seam 



At the coal- face, 320 yards from pit 



In the hohng at the face 



At bottom of upcast pit, 586 metres, or 1922 feet 

 deep 





If we take the mean annual temperature of the district at 10°-6 C, 

 or 51° F., it is clear that, the observations being made when the 

 thermometer at the surface was almost at freezing-point, the tempe- 

 rature of all the workings up to the face of the coal was considerably 

 reduced by the coldness of the in- taken air; and the rate of increase 

 due to the depth can hence only be roughly estimated at one de- 

 gree F. for from 88 to 117 feet. 



Colliery of Bonne Esperance, Montigny. 



Temperature. 



Cent. 



Fahr. 



Fit St. Avgtista, Dec. 7, 1867. — Surface-temperature . . . 

 At depth of 575 metres, or 1886 feet 



9-50 

 11-50 

 19 -00 

 21 -00 



18-00 



32° 



49 



52-7 



66-2 



69-8 



64 -4 





At a coal-face 380 yards from pit 



In waggon-way, behind a door 



At a working to which the an* had travelled 930 

 yards 





* British Association Keports 1861, p. 55. 



