314 THE BLISWORTH CUTTING. CHAP. XV. 



tending with these difficulties, and at length he was 

 compelled to abandon the adventure. The engineer 

 then took the works in hand for the Company, and they 

 were vigorously proceeded with. Steam-engines were 

 set to work to pump out the water ; two locomotives 

 were put on, one at either end of the cutting, to drag 

 away the excavated rock and clay ; and eight hundred 

 men and boys were employed along the work, in digging, 

 wheeling, and blasting, besides a large number of horses. 

 Some idea of the extent of the blasting operations may 

 be formed from the fact that twenty-five barrels of gun- 

 powder were exploded weekly ; the total quantity used 

 in forming this one cutting being about three thousand 

 barrels. Considerable difficulty was experienced in sup- 

 porting the bed of rock cut through, which overlaid 

 the clay and shale along either side of the cutting. It 

 was found necessary to hold it up by strong retaining 

 walls, to prevent the clay bed from bulging out, and 

 these walls were further supported by a strong invert, 

 that is, an arch placed in an inverted position under the 

 road, thus binding together the walls on both sides. 

 Behind the retaining walls, a drift or horizontal drain 

 was provided to enable the water to run off, and occasional 

 openings were left in the walls themselves for the same 

 purpose. The work was at length brought to a suc- 

 cessful completion, but the extraordinary difficulties 

 encountered in forming the cutting had the effect 

 of greatly increasing the cost of this portion of the 

 railway. 



The tunnels on the line are eight in number, their 

 total length being 7336 yards. The first high ground 

 encountered was Primrose Hill, where the stiff London 

 clay was passed through for a distance of about 1164 

 yards. The clay was close, compact, and dry, more 

 difficult to work than stone itself. It was entirely free 

 from water ; but the absorbing properties of the clay 

 were such that when exposed to the air it swelled out 



