WATER-BEARING STRATA. 339 



strong volume of water equal to 300 gallons per minute, 

 under a bed of hard stone, severely taxing the pump. 



This water had now to be dealt with, and it was clearly 

 seen that if the sinking proceeded, with this water coming 

 in, the pump would be overpowered ; it was therefore de- 

 termined to wall this water back. 



Before doing this the sinking was further carried down 

 8 or 10 feet, so as to get well below the water-bearing strata ; 

 and to protect the sinkers and enable the work to proceed, 

 shields of wrought-iron plate, ^-in. thick, were depended and 

 fastened from the curb above, the water being conducted 

 down from behind these shields with temporary bratticing 

 cloths and wooden garlands to the pump suctions, which 

 were made sliding to enable them to be easily accommodated 

 to the gradually increasing depths. 



In this manner the water was conducted down until the 

 fissures through which it issued were passed, this occupying 

 a little over a month, or at the rate of about 2 feet 6 inches 

 a week. 



Another permanent cast-iron curb was now fixed in the 

 manner before described, and from this curb 18 inches of brick- 

 work in cement was raised, the iron shielding being brought 

 down to it, and so allowing the brickwork to be brought up 

 fairly dry, spaces being left at the foot of this section to allow 

 the water to flow to the pump from the back of the wrought- 

 iron shields. As the cement lining was raised, it was allowed 

 time to set, and at intervals cocks fitted into cast-iron boxes 

 built in the brickwork were inserted into spaces behind the 

 walling, from which shoots or piping were carried, which 

 were kept open as the brickwork was raised to allow the 

 water free egress. 



In this manner a tight walling was obtained, care being 

 taken to bring up at the back of the walling pipes of lead , 



