870 Transactions of the American Institute. 



The practice of our modern engineers has corrected some of 

 the causes of the defects in the manufacture of water-pipe, but it i? 

 well known that the metal often put in them is the cheapest in the 

 market, and the specifications and inspection of pipes for many 

 of our water works, show that the engineers who prepare them, 

 either do not understand the quality of the metal best calculated 

 to withstand corrosion, or are restrained from requiring it on 

 account of its higher cost. 



In the removal of the old water-pipes at Albany, in 1851, which 

 had been buried for a quarter of a century, I found some which were 

 excessively corroded, and others so little affected that they were 

 relaid in the new works. The present engineer, Mr. Carpenter, 

 informed me lately, that he had examined some of those which I 

 had laid down sixteen years ago, and found them perfectly sound 

 and uncorrodedj in some cases the paint marks were still bright 

 and legible. I have seen some of the old Manhattan water-pipes 

 taken up in New York, which had been in the earth over forty 

 years, and for twenty-five years without water in them, which were, 

 as the English engineer said, " as sound and uncorroded as the 

 day they left the foundery." Other of these pipes, however, were 

 greatly corroded, and I have seen such badly corroded pipes kept 

 to show that iron was not a suitable material for water-pipes. 



With the experience now acquired, iron piles may be used, made 

 of a proper description of metal, with the assurance that they will 

 last centuries without being sensibly injured by corrosion. 



These piles are usually made cylindrical and of varying sizes, 

 from a few inches diameter up to twenty feet. They cannot be 

 driven to a great depth or through hard material by the machines 

 used for driving wooden piles. 



The pneumatic and hydraulic processes are therefore used, as 

 well as that by excavating from within by machine or hand labor. 

 Dr. Potts procured a patent in England for the former process, 

 about twenty years ago. In his method, the bottom of the pile 

 was open and the top scaled. 



By exhausting the air from the interior of the hollow pile, a 

 downward atmospheric pressure was effected, sufficient to drive the 

 j)ile into moderately soft material. 



In 1850, a bridge was commenced across the ]\Iedwa3', at Roch- 

 ester, England, the piers of which were of hollow cast-iron piles, 



