DISTRIBUTION. 63 



Over the greater part of my career the cast-iron main 

 pipe has been the invariable rule, but within the last ten 

 years I have laid several miles of wrought tube, both with 

 screwed and with socket joints. The advantages of 

 wrought or steel tube, as compared with cast-iron, are elas- 

 ticity, fewer joints and greater strength. Against these, 

 there is the bugbear of durability. It is remarkable that 

 engineers who have always been accustomed to lay long 

 lengths of wrought-iron pipe up to 2 inches diameter will 

 oppose wrought-iron mains on this ground. There is no 

 evident reason why a 4-inch or 6-inch pipe should be more 

 exposed to corrosion than a 2-inch, and, to be consistent, 

 if it is considered that wrought-iron main pipes will not 

 stand, the whole of the service pipes should be laid in cast- 

 iron. Most of the objections to wrought-iron, as to many 

 other things, come from those who have never tried it. I 

 have frequent occasion to examine wrought-iron main pipes 

 that have been laid for some years, and have seen nothing 

 whatever to indicate that their working life will be short. 

 There is some advantage as regards first cost, size for size. 

 A run of 4-inch steel, or wrought, when laid, will cost 

 appreciably less than cast. But the delivery capacity is 

 greater. The pipe being smooth inside, and the breaks for 

 joints less frequent and pronounced, there is very much 

 less skin friction on the inside of the pipe, and under 

 similar circumstances as to diameter, length and initial 

 pressure, wrought pipes will deliver quite 25 per cent, more 

 gas than cast. The difficulty of making sound service 

 connections is another fancied objection. Of the two, the 

 advantage is in favour of the wrought pipe, because the 

 whole thickness is used, whereas with cast iron the hole is 

 apt to be chipped. Two complete threads on a wrought- 

 iron main will be as strong and as sound as the average 



