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.
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.
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).
From the [drawings] it may be seen that the pit is prolonged to the side wall of the building, with steps leading up to the ground-level. The top and sides of the opening are made with galvanised sheeting, forming a kind of short tunnel in which the coolie may stand upright. The outer face of the brick furnace forms the inner end of the tunnel, and accommodates the door of the furnace. The bottom of the pit is filled up with clay and stones almost to the level of the bottom of the door. This ensures a very shallow hearth, and guards against an unduly large fire. Obviously it is not desirable or necessary to make the hearth of fire-bars, as was done in one instance, with the provision of a door below for removing the ash. This would lead only to a strong draught being created, with a high rate of fuel consumption.
Brick and Cement Superstructure of Furnace Inside the
Building, but fed from Outside.