Where the privy-ashpit system is in use--as it still is to a large extent--as much of the contents of the ash pits as can be sold at any price, however small, are collected separately from the drier portions, and sent out of town as manure; but what remains is still too offensive to be deposited on ground near the town; and when it is attempted to collect the excreta separately by the pail system, the process is no less unsatisfactory. These difficulties led to the adoption, under the advice of the late Mr. A.W. Morant, M. Inst. C.E., the Borough Engineer at Leeds, of Fryer's method of destruction by burning--that is, of the dry ashes and cinders and the animal and vegetable refuse. The author was Mr. Morant's assistant. The first kiln was constructed at Burmantofts, 1½ miles from the center of the town in a northeasterly direction, and has been in use since the beginning of the year 1878. In 1879 another kiln was constructed at Armley Road, a mile from the center of the town in a west-southwesterly direction, which has been in use since the beginning of 1880. Each destructor kiln has six cells, three in each face of a block of brick work 22 feet long, 24 feet through from face to face, and 12 feet high. Each cell is 8 feet long and 5 feet wide, arched over, the height being 3 feet 4 inches, and both the bottom and arch of the cell slope down to the furnace doors with an inclination of 1 in 3. The lower end of each cell has about 26 square feet of wrought-iron firebars, the hearth being 4½ feet above the ground. [Illustration: FIG. 2.--CARBONIZER. Section through furnaces. Longitudinal section. Cross section.] There are two floors, one on the ground level, a few feet only above the outlet for drainage, the other floor, or raised platform, being 15 feet above it. The refuse is taken in carts up an incline of 1 in 14 on cast-iron tram plates to the upper floor, and deposited upon and alongside of the destructor, and is shoveled into a row of hoppers at the head of the cells. These hoppers are in the middle of the width of the destructor, and each communicates with a cell on each side of it. The refuse is always damp, and often wet, and after being put into the cells is gradually dried by the heat reflected upon it from the firebrick arch of the cell, before it descends to the furnace. This distinguishes the system from the common furnace, and enables the wet material to be burned without other fuel. No fresh fuel is used after the fires are once lighted. The vapor passes off with the gases of combustion into a horizontal flue between the two rows of cells, through an opening at the head of each cell, alongside that through which the refuse is fed into it, the two openings being separated by a firebrick wall. The refuse is prevented from falling into the flue by a bridge wall across the outlet opening, over which the gases pass into the flue.