chamber, K, of the heater, and also by that drawn in by the rising
column of gas, passing before the orifices, D, which may be regulated
at will. The small burner, I, which is kept constantly alight, heats
the central compartment, K, the sides of which transmit heat to the
gas circulating in the annular casing, L, of the compartment. The
heated gas passes, by the passage, AA¹, into the space, C, where it
becomes intimately mixed with the air entering at OP, and also with
the outer air arriving by the lateral apertures, D.

The _vis viva_ of the jet is diffused through this mixture, which thus
becomes very intimate, when it penetrates into the tubular
arrangement, R; combustion now taking place at the top, while the
refractory cap emits a bright orange light of great steadiness. As it
is not the flow of gas which determines the entrance of the outer air,
the former may be used at any pressure--an advantageous arrangement in
all respects.

When the small burner, I, in the lower chamber is lighted, the
products of combustion issue by the orifice, O, of the compartment,
terminating in a needle like that of the steam injector; and the jet
draws along the air entering the apertures, PP, above the cone. The
gas from the pipe, arriving from the annular space, L, fills the two
lateral pockets shown in dotted lines, and passes through the
orifices, AA¹, which communicate with the upper chamber of the
burner. The manner in which it is conveyed thence to the tubular
arrangement has already been described.

Fig. 2 shows a more simple method of carrying out the same principle,
and of effecting a considerable saving in gas for a given intensity of
light. In this form, a wick, T, impregnated with an alkaline earthy