132 GASOMETERS. 



into another gasometer not yet full, and which, having its curb completely 



immersed, is under less pressure. For example, suppose the weight of 



the gasometer to be thirty-three tons, and its working pressure to be 



2-!%ths inches ; suppose also the weight of the curb in water to be 2\ 



tons, then, when it partly rises out of the water, the working pressure will 



be increased by the weight of so much of curb in air plus 1\ tons, minus 



the buoyancy of so much as yet remains in the water (which ought not to 



be more than two inches) ; this increased pressure will be found to be nearly 



four-tenths of an inch, and quite sufficient to cause the gas to flow into 



another gasometer, having its curb totally immersed. The mains leading 



to the gasometers ought to be all open, and the gas unrestricted by valves, 



which ought only to be closed when a gasometer is undergoing repair ; 



even then I should prefer sealing its inlet- and outlet-pipes by water ; for 



let there be any number of gasometers, even of the same diameter and 



height, their weights, and consequently the resistance they oppose to the 



entrance of the gas, will vary something ; therefore they will not fill 



equally ; the lightest will rise first, and if the next has an excess in the 



working pressure of a little more than four-tenths of an inch, it will not 



rise at all until the curb of the first is completely in action, which I have 



already shown will be in effect equal to four-tenths of an inch. 



All the gasometers should be regulated by weighting them, adding to or 



reducing their curbs, so that they will not vary in their respective pressures 



more than about three-tenths of an inch. If the capacities of the gasometers 



be made equal to the produce of gas in twenty-four hours, and the above 



simple precautions taken, no inconveniences will arise ; no gas will be lost, or 



accidents occur, from negligence on the part of workmen. 



The dimensions of the curb H will be 12 X 12 inches, formed of Memel 

 timber, scarfed and fastened together in segments by trennels, and secured to 

 the sides of the gasometer within three inches of the bottom, so that when it 

 is out of the water ten inches, the sides may be sealed by a head of water five 

 inches, more than is actually necessary, but completely to guard against acci- 

 dent, not more than advisable. 



I is the inlet-pipe, of the same diameter as that leading from the retorts, viz. 

 eight inches. Its mouth above the water-line should be rather higher 

 than the edge of the tank. 



K is the outlet-pipe, twelve inches diameter, entering the gasometer, under 

 the same circumstances as the inlet-pipe. 



