T-o 



UNDULATORY FORCES. LIGHT. 



[OAS-nrRXERS. 



V:,-. 1 



I'll- Hi- 1 . Leslie's Argand is the very re- 



verse of the but; for the principle cut 

 which it is constructed is to allow a 

 current of air to pass up between each 

 of the jeta, and so to destroy, to a cer- 

 tain extent, the continuity of the flame. 

 This is effected by a cumber of small 

 tubes, which riso to tho height of an 

 inch or so above the ring which sup- 

 ports them. These tubes are made 

 to converge a little as they advance 

 upwards, and thus they form a trun- 

 cated cone (Fig. 132). The glasses 

 are constricted, so as to deflect the 

 air into tho flame; and they are of 

 different heights, in order that they 

 may be suited to ditt'cruut amounts of consumption. 

 These uurners are very well suited for 

 the combustion of caniiel gas, but they 

 destroy the light of common gas by over- 

 burning it. The flame should be always 

 managed so as to reach nearly to the top 

 of the glass : for if it pass above it, soot 

 will be deposited ; and if it do not reach 

 almost to the level of the glass, the gas 

 will be overburnt, and light sacrificed. 



14. The Pinnacle Burner, of Messrs. 

 Baldwin and Neal, is constructed on 

 somewhat the same principle as the last, 

 only the tubes are very short : they are, 

 in fact, but mere nipples on the top of 

 the ring, and the glass is not constricted 

 (Fig. 133). 



Many other varieties of gas-burners 

 have been invented ; and as the orifices of 

 the jets are very liable to corrosion from 

 the ammonia and sulphur contained in the 

 gas, Mr. Hallen has proposed that clay 

 or porcelain nozzles should be employed. 

 The relative value of the several kinds 

 of burners, as employed in the combustion 

 of ordinary London gas, as well as that 

 from cannel coal, may be perceived from the following 

 table. The value is represented as per cubic foot, in 

 sperm candles of 120 grains consumption : 



Burner. 

 Single jet . 

 Cockspur . 

 Fish-tail, No. 1 

 No. 2 

 No. 3 

 No. 



Cannel fras : 

 candles per foot. 



2-6 

 30 

 3-0 

 36 

 40 

 43 



Bat's-wing, nearly the same as fish-tai] 

 Leslie, with 28 tubes 3-6 

 Gaumont . . . 4*0 

 Common Argand 15 holes ;40 

 I! Miner's 28 40 



Platow's 16 42 



Guize 26 42 



"Winfield 68 43 



Billows', with 3 slits . 4-1 



Common (ran : 

 candlei per foot. 



15 

 15 

 19 

 20 

 23 

 2-4 



2-7 



23 

 2-8 

 32 

 29 

 3-0 

 2-8 

 2-6 



From this it will be seen, that the simple jet is the 

 worst kind of burner that can be used for the consump- 

 tion of gas; next come the smaller-sized fish-tails, 

 then the bat-wings, and lastly the Argands. The Gau- 

 mont or double fish-tail, and the Billows' or compound 

 bat's-wing, are also very good burners. But it will be 

 evident from the preceding table, that the burner which 

 is best suited for common gas, is not always the one that 

 can be most economically employed for cannel. 



The pressure at which gas ouyht to be consumed is an- 

 other point of considerable importance : for if the amount 

 of pressure be high, the gas will bum with a roaring 

 noise, and will be consumed wastefully ; whereas if it 

 be low, the fish-tail and bat's-wing flames will not be 

 sufficiently spread out, and the light will be dim and 

 sinoky. Dr. Lethcby states, in his Ninth Report to the 

 Corporation of London, that gas ought to bo delivered 



Burner. 



Single jet 



j 



Small fish-tail 



n 

 Large 



n 

 Large bat's-wing 



to the public at not less than half an inch of water pres- 

 sure; and it may be said that, in practice, this is fund 

 to be the beat pressure at which gas can be consumed. 



Again, it is a matter of importance that the pressure 

 at which the gas is supplied to the burner should be as 

 uniform as possible ; for if at oiie time the pressure be 

 great, and at another low, tho burner will require constant 

 attention, in order that the flame shall be of one uni- 

 form height. 



Exprriinents have been made to determine tho rate 

 at which gas burns under diti'urent pressures ; and as 

 the results are somewhat important, they are tabulated 

 below. In a general way, it may be said, that by 

 doubling the amount of pressure, we increase the con- 

 sumption of gas by about half. 



eMui o in inch Consumption 

 of water. per hour. 



0-30 . 2 6 cubic feet 



060 . 3-9 



1-20 . 6-2 



034 . 14 



077 . 2-2 



048 . 23 



097 . 33 



070 . 3-1 



1-40 . 45 



Dr. Fyfe has also observed, that there are certain con- 

 stant relations between the specific gravity of a gas (that 

 is, equivalent to its goodness) and the pressure at which 

 it is burnt, and the time required to consume it that is, 

 provided we use a jet of a given size, and take care that 

 the flame is of a given height. The jet which he prefers, 

 is one having a hole the fortieth of an inch in diameter ; 

 and the height of the flame should be five inches. These 

 relations are as follow : 



1st. The consumption of gas in a given time is as the 

 square root of the pressure; and, consequently, the 

 time required for the consumption of equal volumes, is 

 inversely as the square root of the pressures. 



2nd. The specific gravity of the gas is also inversely 

 as the square root of the pressures. 



'So that if we determine, by experiment, what time it 

 takes for a given volume of gas, of known specific 

 gravity, to burn from a jet of the given size, with a 

 flame of the given height, we are then in a condition to 

 tell the specific gravity, or the rate of consumption, of 

 any other gas, provided it be burnt under the same cir- 

 cumstances, and we observe the pressure. This will be 

 manifest from the following table : 



Pressure in inch Consumption Specific 



of water. per hour. gravity. 



0-6 . . . 0-67 ... -841 



07 . . . 072 . . . -779 



0-8 . . . 077 . . . -729 



0-9 . . . 081 ... -687 



1-0 . . . 086 ... -652 



1-1 . . . 090 . . . -622 



1-2 . . . 0-94 . . . -595 



1-3 . . . 098 . . . -572 



1-4 . . . 1-02 . . . -651 



1-5 . . . 105 . . . -532 



1-6 . . . 1-09 . . . -515 



17 . . . 112 ... -500 



1-8 . . . 115 . . . -486 



1-9 . . . 118 . . . -472 



2-0 . . . 1-21 . . . -461 



By means of this table, we are able to determine the 



rate at which gas is burning, or its specific gravity, by 



merely observing the pressure which is necessary to 



obtain a flame of the given height. In conducting the 



experiment, the pressure-gauge must of course be on the 



jet side of the tap. Dr. Fyfe suggests that we may, by 



operating in this manner, do away with the necessity for 



a meter or a photometer, or both, and that we may 



arrive at results which are approximately correct. Of 



course it must bo understood that the gas is of the usual 



quality, free from carbonic acid and atmospheric air. 



\\hen coal gas is supplied to the consumer at pressures 

 which are variable, or inconveniently largo, the difficulty 



