122 CONSTRUCTION AND MANAGEMENT OF SMALL GASWORKS. 



part of the ground through which they are laid being made 

 up with ashes or town refuse. Localities where there is 

 reason to suspect damage of this nature should be watched, 

 and if another locality for the pipe is unobtainable, it 

 should be protected by being packed in a bed of good 

 fresh earth, or carefully prepared tar and fine, dry ashes. 

 Corrosion is more apt to occur in wrought-iron than in 

 cast; in fact, I know of only one instance of the perishing 

 of cast-iron in virgin soil, and in that case there was 

 reason to suspect the quality of the castings. I have 

 had occasion to take up cast pipes that have been in use 

 for over fifty years, and found them as good as new. Nor 

 have I ever known internal corrosion, such as is sometimes 

 experienced with water pipes. Wrought-iron is liable to 

 corrosion in low-level damp localities, or near the sea, 

 where the soil may at parts be exposed to tidal influences. 

 I have a greater faith in carefully coating the pipe with 

 Dr. Angus Smith's solution than in using galvanized 

 iron pipe. Sometimes it happens that wrought-iron 

 cannot be trusted to remain sound for more than twenty to 

 twenty-five years, and under such circumstances preference 

 should be given to cast-iron. But for many purposes 

 wrought-iron can be safely used, if proper care is taken in 

 the way of applying a preservative. 



More care may advantageously be given to tapping 

 the main and making the connection thereto than is 

 usual, particularly where the joint is subject to vibra- 

 tion ; and if the use of saddle pieces and clips was 

 more general, the unaccounted-for gas would be appre- 

 ciably lower. The old-fashioned plans of cutting out the 

 hole with a hammer and diamond point chisel, or drilling 

 it with a chisel edged drill and cramp, should be discarded. 

 Both of them are open to the objections that they do not 





