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It would also be wise to minimize the handling of the refuse, which is at all tines an unhealthy occupation, and which becomes more so the longer the refuse is stored. At present the refuse is handled three times.
1. In collecting from the house and placing in the dust carts.
2. In removing from the dust carts to the dust boats.
3. In carrying from the dust boats to the dumping ground.
The third handling must continue under the present method of disposal, but might be obviated either by dumping at sea from hopper barges or by burning near the City.
The following objections then are urged against the present method of barging the refuse to the mainland and carrying it to a dumping ground there :—
1. The refuse itself forms a breeding ground for disease.
2. Delays in removal of several days may be entailed by high winds, typhoons and storms. 3. The refuse has to be handled more frequently than by other methods.
Dumping at Sea.
The second method of disposal is that of dumping at sea. To do this would necessitate the use of specially-constructed hopper barges, which would practically take the place of the present dust boats. A sufficient number of barges and tugs would be required, working under European super- vision, as to ensure the removal of each day's refuse within twenty-four hours of collection. The barges containing the refuse would require towing out to sea each day, where the refuse would be emptied, at such a distance as would render impossible any return to the harbour or foreshore.
This method, if properly carried out, is open to fewer objections than that of dumping on land, for no breeding ground for disease is formed and the third handling may be obviated by dropping the refuse into the sea through the bottom of the barge.
There still remains, however, the objection of delays which will occur with every blow or storm, when the refuse for four or five days, or even more, may have to be kept in the City or in boats and barges along the sea front.
Burning.
The most efficient means of disposal is undoubtedly that of destruction by fire, and I believe it possible, by the erection of suitable furnaces to burn the whole of the City refuse within twenty-four hours of collection, and this without risk of delay by wind and storm and with only two handlings. Kurachi in India, where a similar class of refuse would obtain, is burning it successfully, while Penang, Singapore and Madras are erecting Destructor Furnaces,
So thoroughly have the evils of dumping refuse on land, and the advantages of burning it at a high temperature become recognized, that at least eighty cities and towns or vestries in Great Britain have already erected furnaces, while many more in Britain, in the Colonies and on the Continent are either erecting Destructors or are making enquiries in view of doing so.
DETAILS OF FURNACES AND WORKING. Introduction.
Having generally described and compared the three " Methods of Disposal" applicable to Hong- kong I will now deal specially with the proposal to erect Destructor Furnaces and describe such furnaces in detail. Before proceeding, however, I should state that having visited several cities and districts where Destructors are working and seen different patterns, I drew up a specification, which I attach, of the general requirements for Hongkong and asked four of the best known firms to submit designs and estimates. This course was adopted because practically every part of the furnace is patented, while opportunity is given to the different patentees to adapt their several types and patents to the local requirements. Two of the four firms only responded to my request, and the designs, esti- mates, etc., are attached to this Report.
General.
The principal points to be attended to in designing a furnace are:--
1. That the arrangements shall be such, and the heat sufficient, to thoroughly burn the
material and gases and render both innocuous.
2. That such arrangements shall be made as will effectually prevent the escape of dust or
unconsumed fumes from the Chimney.
3. That, consistent with proper burning, the arrangement of furnaces, flues and boilers shall
be such as to obtain the best calorific results.
The Furnace.
In all types of furnace I have seen, the refuse is burnt in the front, while fresh refuse is fed on to a hearth at the back, where it is partially dried before being raked on to the fire and burnt.
In one type of furnace the outlet fluc is at the back and close to the feed opening, so that the heated gases from the fire pass over the unconsumed refuse, thus helping to dry it, but at the same time carrying off unconsumed and noxious fumes to the flue.