Large furnaces are sometimes seen, with flues of brickwork. In view of the foregoing remarks, it will be obvious that these tend to large fires and a rapid combustion, and hence must be classed as undesirable. BRICK STOVES.--Developing from "drum" furnaces, another type comes into existence. In principle it consists of an enclosed brick furnace, with feeding door, and a low conical dome surmounted by an adjustable cap or spark-arrester. The rate of combustion can be influenced by a suitable movement of the cap, which is operated by a screw. This type of furnace has been installed on several estates by the engineering department of Messrs. Harrisons and Crosfield, and is understood to give satisfaction. PATALING TYPE.--With the exception of the "Third Mile" type already mentioned, all the furnaces described are open to a strong objection, in that the coolies have to enter a room, usually filled with hot smoke, in order to attend to the fires. The mere opening of the door of the building is sufficient to fan most fires into a blaze and to raise sparks. Apart from these points, it is natural for coolies to avoid entering too often, with the result that they generally stoke with the maximum load of timber. Even should they not sleep the danger is clearly great. [Illustration: SIDE SECTIONAL ELEVATION (PATALING TYPE OF FURNACE).] [Illustration: PATALING TYPE OF FURNACE.] To obviate these drawbacks, furnaces which are fed from the outside of the building were designed. There have been various forms, but as they were first installed on Pataling Estate, in the present form, they may be known under the description of the Pataling type of furnace. They are eminently satisfactory, and have a low rate of fuel consumption. They are very safe, and in fact, if worked with average intelligence in supervision, can be regarded as being fool-proof. There is practically no ejection of fine ash, and no fine-mesh screens need be employed. They can be adapted to any building having either vertical or sloping walls of galvanised iron. [Illustration: LARGE SMOKE-HOUSE OF ORDINARY CONSTRUCTION, WITH SHIELDED VENTILATORS PERMANENTLY OPEN. In foreground, movable folding racks on which sheets "drip" in the open air. This smoke-house is equipped with brick furnaces fed from the outside (Pataling Estate).] In essential the furnace consists of a shallow pit below ground-level, lined with brick, and having a square brick superstructure rising 4 feet above the floor of the building. On top of the brick walls rests a sheet of boiler-plate perforated with small holes. The hearth being below ground-level, and with the extra 4 feet of height above the floor, it follows that if ash is disturbed it is confined.