BRITAIN'S COAL CELLARS. 93 



apparatus which I have introduced in South Wales, 

 and which, by means of compressed air used as a 

 motive power instead of steam, draws trams and pumps 

 water with complete success, is found to generate ice in 

 an atmosphere which is naturally hot and oppressive. 

 The mechanical usefulness of these new air-engines 

 seems capable of indefinite extension ; while, as their 

 cooling properties form a collateral advantage arising 

 out of their use,. it is at least possible that they may 

 prove valuable auxiliaries to the more regular means of 

 ventilation in extending the security and promoting the 

 healthfulness of our mines. The. difficulties of ventila- 

 tion once surmounted, the extent of coal at our dis- 

 posal is incalculably increased.' 



In the address just quoted there are some striking 

 suggestions as to the possibility of working those coal 

 fields which extend below the sea on our east and west 

 coasts, especially in the counties of Durham, Northum- 

 berland, and Cumberland. Mr. Elliot remarks that 

 4 for all practical purposes these fields are as entirely 

 within the reach of the mining engineer as the ordinary 

 workings out of which coal is hewed.' It is known that 

 in many districts the coal strata extend ten or twelve 

 miles beyond the shore ; and Mr. Elliot believes that by 

 sinking ventilating shafts in the German Ocean the coal 

 below may be safely worked. The idea seems somewhat 

 daring ; yet, after the feats of engineering which have 

 been achieved in our day, there seems no valid reason 

 for doubting that at least when the pressure of a failing 

 coal supply begins to be felt, the means will be found 



