Grimston's burner (shown on the next page) consists, in effect, of an Argand burner turned upside down; the gas issuing from the bottom ends of a number of small tubes placed in a circle. The jets of flame--first directed downwards from the mouths of these tubes--by a conoidal deflector in the centre of the ring, are caused to spread outwards, and assume a horizontal direction; and by their amalgamation with each other a continuous sheet or ring of flame is produced. The horizontal direction of the flame is maintained by its passing underneath a metal flange, faced with white porcelain, or other refractory material; the supply of gas being adjusted so that the flame just terminates at the outer edge of this flange. Before entering the chimney, the products of combustion are caused to flow through a number of vertical tubes contained in a cylinder, which is concentric to an inner cylinder containing the gas-supply tubes. The outer cylinder is traversed by the air needed for the support of combustion, which is to become heated before reaching the point of ignition; and in order the more completely to enable the products of combustion to impart their heat to the entering air, the cylinder is further intersected by strips of wire gauze, which pass around and between the tubes (see fig. 22, on next page). By these means the air is intensely heated; and, passing among the narrow burner tubes through which the gas is conveyed, gives up a portion of its heat to the latter before the point of ignition is reached. Thus, in a very simple manner, both air and gas are raised to a considerable temperature before combustion takes place. With regard to the efficiency of the burner, at the exhibition of gas appliances held at Stockport in 1882 (where a gold medal was awarded to it, as well as to Thorp's burner, to be referred to hereafter), with a consumption per hour of 9·84 cubic feet of 17·5 candle gas, an illuminating power of 60·67 candles was obtained (equal to 6·16 candles per cubic foot); while, on another occasion, when the burner was consuming 8·94 cubic feet per hour, an illuminating power of 51·5 candles (equal to 5·76 candles per cubic foot) was obtained from gas of the same quality. It is claimed for this burner that equally good results are obtained with small sizes as with large; and this, if borne out in actual practice, should go far towards ensuring the success and extensive adoption of the burner. [Illustration: FIG. 21.--GRIMSTON'S REGENERATIVE GAS-BURNER.] [Illustration: FIG. 22.--GRIMSTON'S BURNER. PLAN, SHOWING REGENERATING ARRANGEMENT.] [Illustration: FIG. 23.--THORP'S REGENERATIVE GAS-BURNER.] [Sidenote: Thorp's regenerative burner.]