15 



the arch at the South End of the 

 East Wing. 



There is on the roof an Iron Main 

 of three inches internal diameter, ex- 

 tending along the whole length of the 

 four sides of the Quadrangle, round 

 the Dome, and along the roof over 

 the Elgin Gallery. 



This main has connected with it 6 

 stationary Engines which pump the 

 water into it from cisterns underneath 

 the roof, and these cisterns are in 

 their turn supplied by rising mains 

 connected with the external under- 

 ground pipe, and by that means also 

 connected with the New Eiver Com- 

 pany's Works. Although the water of 

 the New Eiver Company is always on 

 sufficiently to keep the outside under- 

 ground tank and pipes charged, the 

 pressure is not at all times sufficient 

 to drive the water into the cisterns 

 underneath the roof. At some period, 

 however, during every twenty-four 

 hours the pressure is on for a sufficient 

 time to fill all these cisterns which 

 may require water, the supply being 

 regulated by ball-cocks ; so that in all 

 ordinary circumstances they may be 

 calculated on as containing a full 

 supply of water up to the level at 

 which the balls close the cocks. 



