132 TUNNEL1N(J 



hoisted to the top of the open cut by derricks operated by two 

 50 H. P. Lidgervvood hoisting-engines. The pressure pumping 

 plant for supplying water to the hydraulic shield- jacks at each 

 end of the tunnel consisted of duplex direct-acting engines 

 with 12 in. steam cylinders and 1 in. water cylinders, supply- 

 ing water at a pressure of 2000 Ibs. per sq. in. 



