THE miners' friend. 195 



is, cannot easily be ascertained, hecause of the different 

 Nature of the several sorts of Coals. 



As for the Cure of Damps by this Engine, the Air per- 

 petually crowding into the Ash-hole and Fire-place, as it is 

 natural for it to do, and with a most impetuous Force 

 discharged with the Smoak at the top of the Chimney, the 

 contigiotis Air is successively following it ; so that not only 

 all Steams or Vapours whatsoever, that may or can arise, 

 must naturally force its way through the Fire, and so be 

 discharged at the top with the Smoak. But thi^s Motion of 

 the Fire will occasion the fresh Air to descend from above, 

 down all the Pits, and every irhere else in the Mine, but 

 down the Chimney ; provided 3'ou have a heading Drift, or 

 Passage from all the Shafts, or Pits in the Work, to that 

 place where the Engine stands, whether the Mouth of the 

 said Pit and Chimney be lower or higher than the Mouths of 

 any of the rest of the Pits or Shafts in the same Work, it 

 matters not ; for here will be a perpetual Circulation of the 

 Air, and with that swiftness, as is hardly to be helieved. 

 This I have tryed, and know to be true ; so leave the 

 Ingenious Miner to his own Judgment, Whether when all 

 the Air is in a swift Motion, that any Stagnation of Air 

 (which has always been adjudged the cause of Damps) can 

 happen in any Pit. 



Chap. III. 



THE MANNEE OF FIXING THE ENGINE FOE WATEE- 

 MILLS, PALACES, AND GENTLEMENS SEATS 

 AND DEFINING FENS, AND SUPPLYING 

 HOUSES WITH WATEE IN GENEEAL. 



I. For Mills. The Engine must be made and propor- 

 tioned according to the Quantity of Water, required to Drive 

 the Mill you would make Use of. Now suppose you would 

 make a Mill on a plain place, where you will have only a 

 Pond, and a small Spring of Water no bigger than a Quill ; 

 then you must build your Mill-house thirty six foot high, in 

 which you may make what Motions, and what sort of Mills 



