BURNERS. 193 



sume If cubic feet of gas per hour with a flame If inch high, and require 

 1 7^ cubic feet of air for its combustion. The distance between the holes in 

 the drilled ring should be so much, that the jet of gas issuing from each, shall, 

 when ignited, just unite with its neighbour ; beyond this, the number of holes 

 is of no consequence, the size of the burner being computed from its diameter. 

 The diameter of the holes should be about ^nd of an inch. 



Another kind of burner, which produces a very intense light, is the 

 double Argand, similar in make to two common Argands placed one within 

 another, the admission of air to the flames being regulated in the same 

 manner as described above ; the space between the concentric flames should 

 be so small as to require no adjustment, and yet large enough completely to 

 separate them*. A glass chimney must of course form an essential appendage 

 to every Argand lamp, its use being to create a draught and direct the current 

 of air through the flame ; the pressure will be as the height of the chimney, 

 one eight inches high, giving a current equal in pressure to a head of water 

 -^yths of an inch. 



The second series of experiments were made upon a burner represented in 

 Fig. 41, formed of two parallel plates inclining towards each other, so 

 that the gas may be directed towards a point P, about three quarters of an 

 inch above the orifices from which it issues. The space between the plates 

 was just sufficient to admit the proper quantity of atmospheric air ; the sup- 

 ply to the exterior of the flame was regulated by plates having the same effect 

 as the larger cone in the Argand lamp, and adjusted for the proper supply of 

 air in the same manner. The ignited jets of gas proceeding from the drilled 

 parallel plates were separated by the rush of the air between them. The 

 holes in each plate were drilled so that the hole in one plate was opposite the 

 space between two in the other. The light produced was intense, more so 

 than could be attributed to the mere regulation of the air ; nor can I assign 

 any cause why it should be so. Several explanations have been given, but 

 none of them sufficiently correct to form the foundation of a theory. In- 

 creasing the temperature of the atmospheric air supplying the flame I am 

 convinced does not improve the light, provided the regulation is attended to, 

 therefore I cannot agree with those who assign this as the cause. The same 

 brilliancy is produced if two candles are inclined towards each other, so that 



* A burner of this description was fixed on the staircase to the House of Commons in 1815, 

 where it remained until the fire in 1834. 



2c 



