174 



DISTRIBUTION OF GAS THROUGH MAINS. 



on exactly the same level. There were no short bends, and all the services 

 and branches were closed. The pipe measured exactly six miles in length. 

 The leakage was ascertained in the first place by shutting the valve adapted 

 to the returned end, and observing the gasometer ; it was found to be thirty- 

 three cubic feet at the end of one hour, and was allowed for. At the com- 

 mencement of another hour the valve was opened and free passage given to 

 the gas, which was allowed to escape : by observing the gasometer at the end 

 of this hour, it was found that 885 cubic feet had been expended ; deducting 

 thirty-three cubic feet from this for the leakage, 852 will remain for the 

 actual quantity discharged at the end of six miles. This experiment is valu- 

 able to the practical man, both for the unquestionable data it supplies, and for 

 its close approximation to the rules here laid down. 



The quantity discharged by calculation is 

 By experiment 



Difference 



873 cubic feet. 

 852 



21 



TABLES of the different quantities of Coal-Gas of the Specific Gravity '420, 

 delivered in one hour, from horizontal pipes of different diameters and 

 lengths, and under different pressures. 



Quantities delivered by a two-inch Main in cubic feet. 



