INGENUITY AND LUXURY 



a thin facing-layer on ordinary concrete, as even such 

 thin layers are impermeable, and are not affected by run- 

 ning water. A system of conduits made of this mate- 

 rial has advantages over one made of iron aside from 

 that of permanency, one feature being the avoidance 

 of nodules commonly formed in iron pipes. 



In 1886 the city of Grenoble, France, laid about a 

 hundred yards of reinforced-concrete water-pipes in 

 the regular system of water-works. Fifteen years 

 later an examination of these pipes was made. 



"The pipes have at all times resisted, and still resist, 

 the normal pressure of 80 ft. head of water," says the 

 official report. "The length of each section of pipe 

 is 6 ft. 3 in., its thickness, if in., and its internal 

 diameter, 1 2 in. 



"The metal skeleton of these pipes is formed by 

 thirty longitudinal rods in. diameter and by an inter- 

 nal 5-32 in. spiral wire, also an external J in. spiral 

 wire. 



"The sections of pipes weigh 88 Ibs. each. They 

 are connected together with reinforced-concrete rings. 



"On February 2, 1901, a length of 16 ft. of these 

 pipes was raised. Two of the joint rings were broken 

 so as to free two lengths of pipe which had been lying 

 under three feet of ballast. 



"A close examination of these pieces established the 

 following facts : 



"i. The irreproachable state of preservation of the 

 pipes, in which there was found a slight calcareous 

 deposit about 1-16 in. thick. They did no show the 

 least fissure, either internally or externally. 



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