It was considered necessary in some instances to punch a few small holes near the base of the drum in order to ensure a very slight upward draught. In a few cases this perforation has been exaggerated to the form of a hinged door. Unless this can be closed with ease, and is closed according to instructions, part of the object of this type of furnace is defeated; fuel consumption is rapid, and the temperature is too high. In the original form "pot-furnaces" have been found to be effective on many estates, and are still employed with satisfaction. IRON STOVES.--Working on exactly the same principle, on some estates one finds small iron stoves in use. Sometimes broad pipes are attached for the better distribution of the smoke; if this is the case it should be noted that the pipes should have a slight downward slope, and that the "bend" at the end should be turned downwards. In this way condensed moisture and creosotic matter falls to the ground, and does not lodge in the pipe. The life of the conduit is thus prolonged. Usually such stoves are in use where the "head-room" of a smoking chamber is insufficient for other types, or where the nature of the site does not permit of sunken furnaces being installed. They are of value likewise on occasions where the fuel supply is limited to a rich timber such as mangrove-logs ("bakau"), when it is necessary to ensure a low combustion with low cost of fuel. HORIZONTAL DRUM-FURNACES.--To overcome difficulties inherent to drums or "pot-furnaces," the next development was that in which the drum was made to assume a horizontal position, and adapted ingeniously to a simple system of working from the outside of the building. Reference to the drawings given will explain how this is effected. In the first illustration (No. 2) it will be noted that the drum is supported upon brick pillars, with one end projecting through the wall of the building. At the other end a short chimney is mounted, having within it a "damper" which is adjustable from the outside. Over this chimney is suspended a simple baffle-plate, made from a Chinese iron cooking-pan. The outer end of the drum is furnished with a hinged and latched door, in which a small air-regulator is accommodated. In the second set of drawings (No. 1) the drum is increased in size and fitted in a special manner for incorporation with a distinct type of building. Such a scheme was first put into effect by Mr. R. C. Sherar, the manager of Third Mile Estate, Seremban, F.M.S., and for ease of reference the house and furnace will hereafter be mentioned when necessary as the "Third Mile" type. [Illustration: "THIRD MILE" TYPE; HORIZONTAL DRUM. This type of furnace is suitable for adapting to existing buildings with perpendicular lower walls.] [Illustration: "THIRD MILE" TYPE OF FURNACE, USED IN CONJUNCTION WITH "THIRD MILE" SMOKE-HOUSE.]