Gas-Burners , and on the Illuminating Power of the Gases. C X% 
economical. In that with 5 holes, the expenditure for a given quantity of 
light is nearly as great as in a single jet ; and the Glasgow burner of the same 
size and expenditure gives at least 20 per cent, more light. The 10-holed 
burner is better ; yet the addition of four or six holes to it would add to its 
light, without increasing the expenditure. 
Coal-gas burners do not require so many apertures as those for oil-gas, be- 
cause the greater width of the drill compensates for the diminution in number 5 
so that the jets still meet perfectly, and form a uniform cylinder of flame. But 
if the holes are made of less diameter, they must be increased in number ; and, 
within certain limits, the compensation effected in this manner is complete. If 
the diameter be much diminished, however, then there will be a loss, because 
the column of gas becomes very thin, too large a surface is exposed to the air, 
and it burns too vividly. The principle is here precisely the same as that which 
causes a loss when coal-gas is burnt through oil-gas jet burners, (see p. 18.) On 
the other hand, good oil-gas will burn with a flame perfectly united and smooth, 
though the holes are less than the number formerly mentioned, provided they 
are larger. Thus, it burns with a smooth flame from a Glasgow coal-gas burner. 
But then the flame is yellow * ; for the column of gas is too thick, just as when 
it is burnt through a coal-gas jet burner ; and consequently, the charcoal result- 
ing from the decomposition of the gas, does not burn with sufficient intensity. 
It has sometimes appeared to us, that, taking the expenditure into account, 
the yellow flame so formed, gives more light than the brighter white flame 
produced by small and numerous apertures. This, however, we do not state 
positively, as we have been unable to investigate the subject fully. But, at 
all events, it will not on that account become a preferable light; for any small 
saving it may effect, is more than counterbalanced by its comparatively dull 
appearance. 
The remaining points to be attended to in constructing burners are less im- 
portant, and more obvious. They are chiefly the size of the circle of holes, 
-—the length of the burner, — the breadth of the rim, — and the diameter of the 
central air-hole. 
The diameter of the circle of holes, or the size of the burner, will be regu- 
lated by the number o holes. Those used by the Oil-Gas Company of Edin- 
burgh have ten, fifteen, twenty and twenty-five holes ; and, consequently, their 
circles are Jths, x 5 5 ths, x %ths, and x % s 5 ths in diameter. 
The length is not very material. It only operates by affecting slightly the 
central supply of air. Those of the Edinburgh Oil-Gas Company are an inch 
and three quarters long. 
The breadth of the rim should not be great, because in that case the air 
falls at right angles on the column of gas, breaks it, and mixes with the gas ; 
and consequently, a greater proportion of the gas is burnt without previous 
•decomposition. In the burners we have recommended, the rim is J^ths 
broad. Perhaps it might be advantageously made narrower. 
The diameter of the air-hole, if it is cylindrical, must be regulated by the 
diameter of the circle of holes. But as the circle of holes increases, the sup- 
* We mean of course comparatively yellow ; for it is still a bright,, beauti- 
ful flame. 
