Burning Gas for the purpose of Illumination. 296 



neys, are by no means indiflferent matters, but that much ad- 

 vantage may be gained or lost by giving them such forms and 

 proportions as may insure the development of the maximum 

 degree of light which the gas is capable of affording. 



As a general rule, it may be considered that in all burners, 

 whether well or ill made, the gi'eatest quantity of light, in 

 proportion to the gas expended, will always be obtained when 

 the flame has been raised as high as it will go without smok- 

 ing. In proof of this, the following experiment may be made. 

 In any situation where there are three or four burners of the 

 same size, and with similar chimney-glasses, and receiving 

 their gas through a meter (by which the expenditure may be 

 measured), if one of these bm-ners have its flame elevated as 

 liigh as it can be made to burn without smoking, and if , its 

 expenditure per hour be accurately noted on the meter ; if 

 the other two or three burners be then lighted, and their 

 flames be so regulated that their united lighting power shall 

 be just equal to the large flame of the first burner, it will then 

 be found, on noting the expenditure, that it is much greater 

 than in the case of the equal light from the single burner, and 

 that the first burner, which gives light equal to two others, 

 consumes but two-thirds of the gas which they do, or, if it be 

 compared with three others giving together an equal degree 

 of light, its consumption will be little more than half of theirs. 

 It follows from this, that when a certain degree of light is 

 required, such a burner should be employed as is capable of 

 giving this light and no more, and that it is bad economy to 

 use a more powerful burner with a flame of less than its due 

 height. This rule holds good with any number of burners, 

 and is equally true whether they be well or ill made. 



The same rule will apply to the individual jets of an argand 

 burner, as holds in regard to their united eff"ect, and if, in any 

 burner, the jets be of unequal heights, in consequence of bad 

 drilling of the apertures, or neglect of keeping them free of 

 dirt, the consequence will be, that when the flame is raised 

 until the jet from the widest hole reaches the most advanta- 

 geous height, those from the obstructed holes will be consu- 

 ming the gas at a disadvantage, which will be greater or less 



