l cost of the erection of refuse destructors, few
trustworthy data can be given. The outlay necessarily depends, amongst
other things, upon the difficulty of preparing the site, upon the
nature of the foundations required, the height of the chimney-shaft,
the length of the inclined or approach roadway, and the varying prices
of labour and materials in different localities. As an example may be
mentioned the case of Bristol, where, in 1892, the total cost of
constructing a 16-cell Fryer destructor was L11,418, of which L2909
was expended on foundations, and L1689 on the chimney-shaft; the cost
of the destructor proper, buildings and approach road was therefore
L6820, or about L426 per cell. The cost per ton of burning refuse in
destructors depends mainly upon--(a) The price of labour in the
locality, and the number of "shifts" or changes of workmen per day;
(b) the type of furnace adopted; (c) the nature of the material to be
consumed; (d) the interest on and repayment of capital outlay. The
cost of burning ton for ton consumed, in high-temperature furnaces,
including labour and repairs, is not greater than in slow-combustion
destructors. The average cost of burning refuse at twenty-four
different towns throughout England, exclusive of interest on the cost
of the works, is 1s. 1 1/2d. per ton burned; the minimum cost is 6d. per
ton at Bradford, and the maximum cost 2s. 10d. per ton at Battersea.
At Shoreditch the cost per ton for the year ending on the 25th of
March 1899, including labour, supervision, stores, repairs, &c. (but
exclusive of interest on cost of works), was 2s. 6.9d. The quantity of
refuse burned per cell per day of 24 hours varies from about 4 tons up
to 20 tons. The ordinary low-temperature destructor, with 25 sq. ft.
grate area, burns about 20 lb. of refuse per square foot of grate
area per hour, or between 5 and 6 tons per cell per 24 hours. The
Meldrum destructor furnaces at Rochdale burn as much as 66 lb. per
square foot of grate area per hour, and the Beaman and Deas destructor
at Llandudno 71.7 lb. per square foot per hour. The amount, however,
always depends materially on the care observed in stoking, the nature
of the material, the frequency of removal of clinker, and on the
question whether the whole of the refuse passed into the furnace is
thoroughly cremated.

[Sidenote: Residues:]

The amount of residue in the shape of c