20 Drs Christison and Turner on the Construction of 
these the holes are too narrow ; not only is there a positive loss of light, but 
it is likewise exceedingly difficult to drill them uniformly. 
This leads us to observe, that, next to the diameter of the holes, the most 
important point to be attended to in drilling them, is their uniformity. When- 
ever some of the holes are wider than the rest, even though the difference be 
very trifling, the flame has a tendency to shoot out in points from the wide 
ones ; consequently, before the general flame can be raised to its favourable 
elevation, these points become brown and smoke ; and, therefore, if the flame 
is turned down low enough to prevent smoking, it burns with a wasteful ex- 
penditure. An oil-gas burner should never be received from the tradesman, 
unless its flame, at the height of 2h inches, is of nearly equal height on all 
sides. 
The next point in the construction of the burners, is the distance at which 
the jet-holes should be placed from one another. 
The first fact to be noticed under this head, is, that the light increases in 
a greater ratio than the expenditure, when several jets are united together in 
an Argand burner. Mr Brande has made the same observation in his paper 
in the Philosophical Transactions for 1820. He remarks, that, while a single 
jet of olefiant gas, giving a light equal to one wax-candle, consumed G40 cu- 
bic inches, an Argand burner with 12 holes, giving the light of ten candles, 
consumed not 6400, but only 2600 cubic inches. In like manner, an oil-gas 
jet, giving the light of one candle, consumed 800 cubic inches ; while, in a 
12-holed burner, which gave the light of eight candles, the expenditure was 
not 6400 but 3900 cubic inches. That is, for equal expenditures, the light of 
the jet was to that of the burner as 100 to 246 in the case of olefiant, and as 
100 to 164 in the case of oil-gas. 
Both of these proportions, however, and especially that for the olefiant 
gas, are stated too high. Mr Brande burnt the gas in the Argand burner 
with the most favourable height of flame ; but in the jets the flame “ was re- 
gulated by means of the stop-cock, so as to produce a fight equal to that of a 
wax-candle burning with full brilliancy,” (p. 21.) Now, at its most favour- 
able elevation in a jet, even oil-gas gives a light fully equal to two wax- 
candles ; and olefiant gas will of course give more. Hence, when Mr Brande 
made the fight of the jet the same as that of the wax-candle, he must have re- 
duced it to a very unfavourable elevation ; and, consequently, the expression 
for the relative fight of the Argand burners turns out proportionally high. 
"We have found, that, when oil-gas was burnt with the most favourable height 
of flame, in jets and Argand burners of the best construction, the ratio of its 
fight, deduced from a great number of experiments, varied from 100 : 140 to 
100 : 150. When coal-gas is burnt under favourable circumstances, the ra- 
tio is very nearly the same ; and it thence appears that the gain, arising from 
the use of Argand burners over jets, is about one-half per cent, for gas of every 
quality. 
The advantage derived from combining the jets together in the form of 
an Argand burner is very different, according to the interval left between 
them. When they are so distant that their flames do not meet, no advantage 
is gained. This has been taken notice of by Mr Brande. But he seems to 
hint, that every possible advantage is gained, if the flames simply meet, ( Phil 
