The Grimston regenerative burner looks like an inverted argand burner. The gas is brought down a central tube, and the products of combustion are carried away through a tube which lies round it, and the air required to feed the burner is brought through passages in this latter tube which are heated by the products of combustion in their course. The light is enclosed in a half globe, and the products may be carried away into the outer air, so that the light need not injure the air of the room in which it is burned. A very remarkable feature about these regenerative arrangements is that the temperature of the outflowing products of combustion at the top of the tube is so low that the hand can be held over the top of the tube without any unpleasant sensation of heat; and the combustion appears to be so perfect that even if the products are not removed from the room, there is much less unpleasantness than with ordinary gas-burners. Other very important regenerative burners are that bearing the name of F. Siemens, the Fourness (S. Gratrix, jun., and Bro., Alport Town, Manchester), and the well-known Wenham (Wenham Co., 12 Rathbone Place, W., and Milne, Sons, and Macfie, 2 King Edward Street, E.C.), two forms of which are shown in Figs. 56 and 57. Sugg’s “London Argand” and “Cromartie” burners are sufficiently familiar to need no description, and are made in a great variety of designs. The “Osborne” pattern is shown in Fig. 58. [Illustration: 56. Wenham Pendant Light. 57. Wenham Standard Light.] Incandescent gas lamps, even if burned in contact with the air of a room, present certain hygienic advantages. In the first place, the air required for combustion is brought into the room from the outside, in the proportion of six volumes of air to one of gas, and therefore the oxygen in the air of the room is not consumed for combustion. In the second place, the gas is consumed in a very perfect manner, so that the injury to the air of a room produced by the combustion is reduced to a minimum. These lights can be placed wherever ordinary gas-lights can, and it is probable that from the hygienic and photometric value of this class of light it is destined at no distant date to replace ordinary gas-burners. The principle of construction is as follows. In the flame of a Bunsen burner is placed a hood of cotton webbing, previously steeped in a solution containing oxides of zirconium, lanthanum, &c. The average consumption in each burner is 2 ft. gas per hour at 9/10 in. pressure, with an illuminating power of 17 candles. The Albo-carbon light, Fig. 59, (74 James Street, Westminster), consists in superheating ordinary gas and carburetting it by admixture of the vapour generated from the albo-carbon material, which is stored in a reservoir that can be attached to any existing fittings. By its means, the light is very much intensified, steadied, and purified, at very small cost for albo-carbon with a reduced consumption of gas.