Mr. M. Dunn on the Sinking of Preston Grange Engine Pit. 229 



The metals, in the upper part of the district, and where bending in 

 undulating lines over the ridges of the country, are, indeed, very open ; 

 they seem, as it were, broken and disjointed, and, of course, pass water 

 through for remarkable distances, but towards the bottom of the basin, 

 and wherein is situate Preston Grange Pit, the stratification assumes a 

 different feature, lying apparently regular, and being for the most part 

 close and impervious to water. 



Depending, therefore, upon the principle of beating the water in de- 

 tail, by the application of tubbing, and trusting, also, to the chance of 

 meeting with suitable strata wherein to place it, we commenced the 

 winning of Preston Grange Pit, in January, 1829, upon the following 

 scale of preparation : — 



1. The Main Shaft to be 10 feet diameter ; 4i was to be bratticed off' 

 for the engine pumps, leaving 5h for the Coal Shaft. 



2. Pumps varying from 12 to 13 inches, according to their position in 

 the shaft. 



3. The Pumping Engine Cylinder, double powered, and high pressure, 

 26 inches diameter (about 60 horse power), with a stroke of 7 feet, and 

 furnished with 3 boilers, each 20 feet long and 6 feet diameter ; equal, 

 in short, to command 400 gallons of water per minute. 



4. A Winding Engine, 20 horse power, also high pressure, to work 

 with flat ropes, and provided with a temporary Pumping Beam, until 

 the Main Engine should be gotten ready for work. 



5. Crabs, Gin, 5-fold Ropes, and Sheaves, and other apparatus for 

 hanging the Pumps, were provided in the most approved and substantial 

 manner. 



Before proceeding with the narrative, I may, perhaps, be allowed to 



glance at the origin and improvements which have terminated in the 



present system of tubbing, or the stopping back of water. The earliest 



application, and from which the name of tubbing seems to have been 



derived, was the spiking of 2i or 3 inch planks (properly dressed to the 



sweep of the pit) on to cribs of 6 or 8 inches square, placed at intervals 



* By brattice is meant an air-tight wooden partition from the top to the bottom of the 

 shaft. 



