16 Drs Christison and Turner on the Construction of 
It appears, therefore, that the same quantity of coal-gas gives one-half more 
light in a jet of 5 inches than in one of 2 only ; and that nothing is gained by 
lengthening it beyond 5 inches. 
The same fact is equally illustrated by the following series with oil-gas, in 
which the standard was an oil-gas jet of & inches, and the varying light was 
increased successively from 1 to 5 inches. The light and expenditure of the 
standard being taken as formerly at 100, the numbers were, 
1 -inch. 2-inch. 3 -inch. 4 -inch. 5-inch. 
Light, - - 22 63.7 96.5 141 178 
Expenditure, - - 33.1 78.5 90* 118 153 
By calculation from these numbers, the following proportions are procured 
for the light of an equal quantity of gas at each elevation, 
100 122 159 181 174 
That is, the same quantity of gas in a 4-inch jet gives nearly twice as much 
light as in a single-inch jet, and one-half more than in a jet of 2 inches (148 
to 100). The increase appears therefore to be exactly the same as with coal- 
gas ; but it ceases at an elevation of 4 inches. The specific gravity of this 
gas was 910. 
Secondly, The augmentation of the light in a ratio greater than that of the 
expenditure is much more remarkably exemplified in the case of Argand’s 
burners. Thus, the following results were obtained with coal-gas, by elevat- 
ing the flame of a 5-holed burner successively, from half an inch to 5 inches. 
The standard was a 4-inch coal-gas jet, and, as before, its light and expen- 
diture are taken at 1 00. 
\-inch. 1 -inch. 2-inch. 3-inch. 4-inch. 5-inch. 
Light, - 18.4 92.55 259.9 308.9 332.4 425.7 
Expenditure, - 83.7 148 203.3 241.4 265.7 318.1; 
from which the following numbers may be derived, for the relative light of a 
given quantity of gas in such a burner at various elevations, 
100 282 560 582 582 604 
That is, the light is increased six times, for the same expenditure, by 
raising the flame from half an inch to 3 or 4 inches ; but little or nothing is 
gained by raising it higher in this description of burner. The specific gravity 
of the gas was 605. 
With oil-gas, too, the gain is equally remarkable. A 3-inch jet being taken 
for the standard, and the flame of a 15-holed (No. 1. Edinburgh Oil-Gas 
Company) burner being raised successively from half an inch to 2£ inches, be- 
yond which it could not be raised without smoking, the following data were 
procured : 
* This expenditure is someAvhat less than that of the standard 3-inch jet, 
because there was a slight leak in the standard gasometer. This cause of er- 
ror, of course, does not affect the relation of the several expenditures of the 
moveable jet to each other. 
