166 DISTRIBUTION OF GAS THROUGH MAINS. 



DISTRIBUTION OF GAS THROUGH MAINS. 



THERE is no branch of science connected with the subject of gas engineer- 

 ing so highly important as that which relates to its conveyance and distribu- 

 tion through pipes ; there is none in which theory affords more assistance, 

 and there is hardly any branch to which so little attention has been paid. 

 The interests of the Company are not best served simply by increasing the 

 quantity of gas from the same quantity of coal, or improving the lime- 

 machine, etc. The laying of street-mains forms the most considerable item in 

 the outlay, and, by a judicious arrangement in the first instance, much may 

 be saved both at first and last. 



It is to render this branch of the science and that of the passage of gas 

 through pipes perfectly plain, that the following pages are written. I hope 

 even those previously unacquainted with the subject will find rules and data 

 contained therein by which their practice may be regulated under every pro- 

 bable variation of circumstance. These data are not founded upon theory 

 alone, nor are they advanced with any wish to change existing systems (if 

 there be any) ; they have been proved to be correct by many years of unin- 

 terrupted practice, and I therefore invite my readers to follow the reasonings 

 and examine the principles upon which they are based. 



When it is proposed to light any town or district of a town, with gas, the 

 first step to be taken is to ascertain the number of lights, both public and 

 private, that will be required, with as much accuracy as circumstances will 

 permit ; the length of time such lights will have to burn, and the quantity of 

 gas consumed by them per hour, making allowances for the increase of lamps 

 that will probably be required by the extension of the town. The size of the 

 works themselves may be easily ascertained from this calculation ; it will then 

 remain to fix upon a proper situation in which to erect them. The best local 

 position is upon the banks of a navigable river or canal, and at the lowest 

 available level. It is not possible to give a decided rule for the choice of 

 situation, because the value of ground, and difficulties in many cases con- 

 nected with purchase, title, etc., will throw obstacles in the way, but the 



