158 



VALVES. 

 Fig. 37. 



D is a cast-iron plug, closed at the top by a hinged lid, and driven firmly into 

 the wooden block. 



The price of these valves is usually about 20s. for every inch in the diame- 

 ter up to twelve inches, beyond which size they increase 10*. for every inch. 

 Thus a twelve-inch valve costs 12, and a sixteen-inch valve 14. 



If no valve happens to be contiguous to the spot where a main should re- 

 quire repairing, a simple and efficacious contrivance of Mr. G. Lowe may 

 be had recourse to as a substitute. For example, supposing that a fractured 

 pipe had to be taken out from the middle of a long run of main, or a junction 

 had to be made with another ; drill a hole about \\ inch in diameter upon the 

 top of the pipe, on each side of the space to be taken up ; through these holes 

 insert empty bladders furnished with small tubes and stop-cocks ; when these 

 bladders are inflated, by blowing into them through the tubes, they will fill up 

 the mains and stop the exit of the gas almost perfectly, and form an excellent 

 temporary valve. When the repair is finished, withdraw the bladder, and 

 stop up the drilled hole either by screwing a pin, or driving a wooden plug 

 into it. 



