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Croton Aqueduct Department, Engineer's Office, ) 

 New York, Sept. 18, 1852. \ 



To Messrs. Thomas 0. Le Roy & Co. : 



Gentlemen — According to your request, I have made experiments 

 upon pure tin service pipe, now manufactmed by you. To test its com- 

 parative as well as positive strength, I had two pieces of pipe, one tin 

 and the other lead, joined together, so that the two composed one 

 length, every part of which would be subjected to the same strain, un- 

 der any experiment tried, and in order to test at the same time, in re- 

 gard to the tin pipe, the efficiency of what is called a " wiped joint," 

 the tin portion was cut in two, and a " joint" wiped on it in the manner 

 usual with lead pipe. All conditions of both lead and tin pipe being 

 thus provided for, the length was connected with one of our hydraulic 

 proving pumps, the regular load of which is 300 lbs. (three hundred 

 pounds) to the square inch. From this point different experiments were 

 made, until the pump was worked up to ten hundred and fifty-eight 

 pounds (1058 lbs.) to the inch, at which point both lead and tin pipe 

 remained unaffected. The pump was now worked up to pressure of 

 1104 lbs. (eleven hundred and four pounds) to the square inch, when 

 the lead pipe burst. The tin pipe, however, remained unchanged. Un- 

 der the closest examination, no sign of imperfection could be perceived 

 in the joint; and the appfication of the calipers to the pipe proved that 

 no part of it had been in the slightest degree enlarged. 



I may here add, that the " wipe" joint was afterwards cut and exam- 

 ined by me, and proved to be by no means one, in the making of which 

 great care seemed to have been used, but rather to the contrary. The 

 thickness of the tin pipe thus tested was 3-32ds (three thirty-seconds) 

 of an inch ; its bore 5-8 (five-eighths) of an inch. The lead was what 

 is known as "extra strong," and its thickness was 7-3 2ds (seven thiriy- 

 seconds) of an inch, and its bore 5-8 (five-eighths.) 



The result of these experiments seem to me conclusive. You have 

 obtained what has long been the great desideratum in the water service 

 of this city — a pipe which will not afi'ect, nor be affected by the water, 

 while it has all the advantages which malleability and strength give to 

 lead for service pipe in om- houses. The only obstacle heretofore ex- 

 isting in the way of tin pipe, has been its cost. This, you have hap- 

 pily been able to overcome. The cost of manufacture you have de- 



