224 



ACTUAL COSTS AND CAPACITY OF GASWORKS. 



blocks. All the joints of the purifiers are machine-faced, 

 and jo : nted with cement when erected. Where exposed 

 to sight, all bolts have hexagon heads and nuts, the latter 



Fig. 27. Purifier Valves : Elevation. 



Fig. 28. Purifier Valves : Plan. 



of full thread, with an iron washer underneath. The 

 wrought-iron used in the work was specified to be equal 

 to the. best Staffordshire, and to be capable of bearing a 



