€34 Mr. M. Dunn on the Sinking of Preston Grange Engine Pit. 



Little or no more water was met with below here during the sinking, 

 but at the depth of 55 fathoms a second column of pumps was converted 

 into another fixed set, and the third column attached in its turn as the 

 sinking set. 



On the 1st of December, 1831, nearly two years after the commence- 

 ment of the undertaking, the Coal was passed through at the depth of 70 

 fathoms, at which period, and ever since, the total water does not ex- 

 ceed 50 gallons per minute, or one-eighth part of the engine's power. 



TABLE OF THE DIFFERENT TUBS AND THEIR EFFECTS. 



1 Tub, 



2 Ditto, 



3 Ditto, 



4 Ditto 



Total, 



Weight per Seg- 

 ment. 



Weight 

 per Fath. 



cwt. qr. lb. 



2 



2 2 



2 3 



3 2 



CWt. 



48 

 60 

 66 

 80 



I Quantity of 

 Faths. in Water per 



Length. 



Minute 



Bottom of 



Tub, 



depth from 



Surface, 



8 

 6£ 



4" 

 41 



galls. 



200 

 300 

 300 

 350 



23 



1150 



faths. 



9 

 28 

 36 



44 



SECTIONS OF GREAT SEAM. 



Sp. gravity. Ft. In. 



1-26 Coal, called Splint, 2 10 



Slaty Band, 3 



1-27 Coal, called Cherry, 3 



1-44 Parrott, or Gas Coal 7 



Coal, good, 8 



7 4 



Ft. In. 



3 



b 



3 1 



9 



9 



8 



Since the completion of the pit, the driftings have extended north, 

 south, and east, about 80 yards each, the Coal rising about one in eight, 

 but no symptoms appear of any leakage of water, although at this mo- 

 ment the adjoining colliery of Walliford, distant less than a mile, is 

 drowned up, and the water standing 80 fathoms above the level of the 

 Coal. The colliery seems, therefore, secure from the irruption of any 

 of the waters before-mentioned, except one or other of the following 

 causes should, by possibility, occur. 



