to burn utilizes this one-tenth of the heat values, and makes the operation quicker and more economical.

If, now, to this dried charge of garbage be added a proportional amount of dry refuse, there is sufficient bulk of material to maintain combustion with little or no additional fuel; and this is precisely what is accomplished by the latest type of the American furnace.

In this improved refuse and garbage destructor there is provided a drying chamber, placed behind the front compartment, which receives the charge of saturated garbage. By dividing the lower longitudinal section of the furnace by a bridge-wall, it is possible to make the front compartment an enlarged fire-box, kept supplied with dry refuse, into which the charge of dried garbage is brought forward. The consumption of smoke is provided for by suitable combustion chambers divided by fire-brick latticework, which transforms all combustible elements into carbonic dioxide.

The results of the whole operation are to utilize the combustible refuse for fuel by drying and burning out successive charges of garbage, maintain the temperature, deliver the heat where most effectually employed, and thus, with no additional cost for labor, reduce the cost of operating to a rate far less than by the former methods.

c. The value of city rubbish or dry refuse is just now becoming understood and appreciated. Nearly everything discarded from the household, if separated and properly handled, has a market value and can be turned to some useful purpose. Within the past year a practical and satisfactory method of making this separation has been devised and put into use, and in two cities works have been established and are now operating.

The history and results reported from the Refuse Disposal Station of New York City will be the subject of another paper, and need not be here described. The construction, in another city, of a larger and more efficient plant devoted entirely to this work is most significant as a sign of progress in the art of waste disposal, and as indicating what will be the future action on this question. What is now being done in New York and Boston can be done anywhere with equally good or better results.

THE BOSTON REFUSE DISPOSAL STATION.

In 1895 the Board of Health of the City of Boston recommended the erection of a furnace to destroy the combustible waste which was then dumped with the ashes at various points or conveyed in scows down the harbor and thrown into the sea. The board renewed this recommendation in their reports of 1896-97, and in April, 1898, the city advertised for bids for the disposal of this waste by cremation, estimating the amount at 500 cubic yards, and stipulating that the work should be done at one of the dumping boards. The four bids received were rejected as unsatisfactory, but in the September following plans were presented for a refuse disposal station, which were accepted, and subsequently a contract was made with a private company to carry out these plans by special contract.*

Through the courtesy of Mr. O'Shea, Superintendent of the Sanitary Division of Boston, I am able to give some exact details of collection service there that will be useful for comparison.

The refuse is collected from an area included in a circle of two miles from the City Hall, containing all the business district and a proportion of the resident section, the population of which is 140,000 and covering ninety-five miles of streets. The collection is made daily by twenty-four special carts holding 4 cubic yards, drawn by one horse, attended by one man. The daily number of loads varies with the season, the largest day-in Octoberbeing 140 loads=540 cubic yards; the smallest-in January-12 loads=50 cubic yards. The total number of loads from March Ist to Sept. 1st, 1899, was 7,888.

The average for the summer months may be taken at 52 loads -217 cubic yards-weighing 807 pounds net per load, or about 22 tons daily.

For the same territory and the same period-142 working days -there was collected 68,118 loads of ashes weighing 1,943 pounds per load, and 14,363 loads of household offal (separated garbage), weighing 2,300 pounds per load.

Assuming the component parts of this refuse to be the same as in New York, then 35 per cent. would be marketable; 60 per cent. is combustible for fuel; 5 per cent. is worthless, and must be

* Description of this process and the terms of its employment were described in detail by your reporter at the meeting of the Medical Society of the State of New York, Albany, February 2, 1899. Published in THE SANITARIAN, March and April numbers, 1899.

hauled away with the ashes from the destructor-which is about 17 per cent. in weight of the original bulk of material collected. and brought to the works.

d. The utilization of the surplus heat from the cremation of refuse is a factor which must henceforward be taken into account in all aspects of this question. With the single exception of the two waste-disposal stations in New York and Boston, there are no cremating furnaces in this country that utilize the heat from the refuse, and in these only a fraction of the power is employed. Without a lengthy test of this value of waste as fuel we cannot accurately estimate the amount of power obtainable from a given amount, but enough is now known to indicate that a great saving can be made by the adoption of measures that are proven to be successful.

Taking as the average 200 cubic yards daily collection from 200,000 people, and selecting out 35 per cent. of this as marketable, there remains in bulk 120 cubic yards to be burned. In weight this will exceed the average of 207 pounds per cubic yard, since it includes matters and articles of no value for sorting, but burnable for fuel. Barrels, boxes, bits of wood and coal, sawdust, berry crates, broken furniture, oil-cloth, matting, old carpeting, mattresses, excelsior, paper of all kinds and quality in small pieces -but large in the aggregate amount-comprise the discarded refuse.

This material fed continuously into a destructor will produce a temperature of over 2,000 degrees. Under this temperature glass, iron, sand-dirt, stone and bits of coal, if allowed to enter the furnace, will fuse into a semi-liquid mass and form clinker, that has to be subsequently broken up and removed. A boiler of 60 horsepower is maintained at maximum pressure, and the dampers must be kept open for escape of surplus heat.

There can be no doubt but that 100 horse-power can be developed and maintained for ten hours with this amount of fuel. In New York the conditions are much the same, though only the lightest parts of the refuse are burned. Probably not more than 60 cubic yards in 10 hours are destroyed, and 75 horse-power is obtained-of which less than 10 is employed.

English engineers have for years past experimented on the fuel value of various wastes, and their reports have a peculiar interest for us, since they represent accurate tests by experienced men of

high professional standing, and are officially reported for the information of the municipalities ordering the trials.

The following tabulated reports of disposal of seven different. places give a clear idea of the quantities of refuse, the water evaporated, the cost of operating, and the uses for power developed.

An examination of these and other reports show that every variety and class of municipal waste is destroyed without nui-. sance at small cost, and that the heat produced is turned into power. It appears that about 10 pounds of unsorted town refuse and 20 pounds of mixed sewage sludge and unsorted refuse are each equivalent in fuel value to one pound of coal.

There is about 33 per cent. of residuum in weight, and 25 per cent. in bulk, left of the original amount, and this has some value. for commercial purposes or municipal uses. The heat units in one pound of waste will evaporate one pound of water, though this, of course, varies with the presence of moisture, of fine dust in the waste, and other conditions.

SUMMARY OF DISPOSAL WORK IN ENGLISH CITIES.

At the beginning of this year there were eighty-one cities and towns in Great Britain employing cremation as their chief means for waste disposal. There were in use 867 cells, or separate small furnaces; and reckoning each of these to destroy 6 to 8 tons daily, then something like 2,250,000 tons of unsorted house refuse and sewage sludge are annually burned.

Of these eighty-one places, seventy-six utilize the heat developed by cremation for one or another useful purpose. Fourteen cities use the power for electric lights in the works, and eleven employ it as an auxiliary to the electric power plant of the place. At fifty-two places there are mills that grind the ashes and clinker for mortar, or crush it to suitable size for making roads or footways. As a basis for concrete work and as a substitute for sand, blocks made with destructor dust stood a strain of 40 per cent. greater than when made with sand and pebbles.

There are six cities and towns employing the steam from disposal works in the city disinfecting station-a practical and economical purpose of the highest utility and benefit. Seven places utilize this force for manufacturing manure, and eight for running the city workshops and forges. In the larger cities, to save expense in hauling, the disposal stations are multiplied, being