GAS-LIGHT.

')G3

g as ( ^’’hout being let off in its way by burners, that is, to the mains which conduct the’hen f P* aces ""here it is to be used. If the main sends off branches for burners,toav b° r ^ le same length the diameter may be reduced, or for like diameter the length’hrou t“ reater " Tor example, if a pipe of 5-32 inches, which transmits 2000 cubic feetr erna' i a length of 2000 feet >' gives off, in this space, 1000 cubic feet of gas; then thender of the pipe, having the same diameter, can continue to transmit the gas through

etl §th of 2450 feet = with undiminished pressure fo^the purposes of light-ing, t \ A* /

ofV ef Aversely, the diameter should be progressively reduced in proportion to the numberSnn S6nt * n lbe ^ en S’h °f ’he pipe.

Point r Se> ^? r ’ nstanee ) ’he gasometer to discharge 2000 cubic feet per hour, and the lastto then ** le ^ ets t0 be at a distance °f 4000 feet. Suppose also that from the gasometerdi an) | rs ’ point of lighting, the gas proceeds through J000 feet of close pipe, thepose t)f r °f tbe P’P e will he here 4-47 inches; in the second 1000 feet of length, sup-thi s , ae P‘P e to give off, at equal distances, 1000 cubic feet of gas, the diameter inthird en = t * 1 (calculated at 1500 cubic feet for 1000 feet long) = 3-87 inches; in the(r ec j, n e ^ en ’ °f 1000 feet, 600 cubic feet of gas will he given off, and the diameterlast s „ nin S ~00 cubic feet for 1000 feet long) will be 2-65 inches; in the fourth andinch 200 cubic feet in 1000 feet long) the pipe has a diameter of only an

beincr a half, for which, in practice, a two-inch cast iron pipe is substituted; thisSertecI ' smallest used in mains, into which branch pipes can be conveniently in-•Jh '

mi’tjj Sarne relations hold with regard to branch pipes through which the gas is trans-a "Sula Int ° ^ddiags and other places to be illuminated. If such pipes make frequenthalf ’ Urr| ings, whereby they retard the motion of the gas, they must be a third or a. '“ er in diameter. The smallest tubes of distribution are never less than one

for

IVjj an inch in the bore.

Ular In re ,’- . otn one central gas work, a very great quantity of light is required in partic-bej n „ a hties, ’here ought to be placed near these spots gasometers of distribution, which,' v *’hout ^ dur ’ n § ’he slack hours of the day, are ready to supply the burners at night,b ma M n S an y considerable demand upon the original main pipe. Suppose the firstthe (l| s , e re luircd to supply 8000 cubic feet in the hoar, for an illumination of 8 hours, ator three* 1106 2 ®®® feet, a P’Pe’lOJ inches in diameter would be necessary ; but if two’he g as -gasometers of distribution, or station gasometers, be had recourse to, into whichfr° m t |j aui 'ing the course of 24 hours would flow through the same distance continuously’bird of e R C n ntra * gas works, the quantity required per hour from them would be only oneinches = 2666'6 cubic feet; consequently the diameter for such a pipe is only 6-15

a half*!’ 6 Principal as well as branch pipes, whose interior diameter exceeds an inch and” is a re mac * e °f cast iron from 6 to 8 feet long, with elbow pipes cast in them whereSocket a essar y- These pipe lengths are shown in fig. 492, having at one end a wide’He other * n6 3t . °” ler a nozzle b, which fits the former. Afier inserting the.one inat ^ Ie * r proper horizontal position, a coil of hemp soaked with tar is driven

of lead i 116 ■ )uac ’* on ; then a luting of clay is applied at the mouth, within which a rings east into the socket, which is driven tight home with a mallet and blunt chisel.

492

The ■

■"° °r three Proved by a force pump before being received into the gas works;

„„ - . - ...euiu oe proved by a force ,—-• —hem'down, and they should

L ? r ’Irree lengths of them should be joined before lay’ = in<J a ff ec ted by changes

of S aCed at least two feet below lhe su r face > t0br , eV f n wV nr internal distribution, whente Wperature, which would loosen the joints. The tubes for mt

Sn »U size, are made of lead, copper, wrought iron, or tin.