nel in the china or earthenware vessel holding the filtering material, as is the case in other filters. The water first passes through a silicated carbon block, and then falls in the form of a shower on to the surface of a layer of some loose silicated carbon supported upon a perforated plate which is not flat, but has elevations here and there on its surface. The result is, that not only when the water is drawn off by the tap does air pass through the filtering material into the filtered water-chamber, but also as the water flows through into this lower chamber it forces the air out through the filtering material itself, which it is enabled to do by means of irregularities on the surface of the plate upon which the filtering material rests. If this plate were quite flat as it was heretofore made, and if there were no air-pipe from the lower chamber, a balance would be established and both water and air would cease to pass through the filtering material.

When rain-water is used for drinking, and even for other domestic purposes, it is advisable to filter it, and a very good filter for this purpose is one devised by Professor Rolleston, of Oxford. The tank to receive the rain water has two compartments, divided from one another by a vertical partition, and each having a horizontal layer of filtering material, as charcoal, placed on a perforated support half-way down the tank. The rain-water pipe from the roof is brought down through this filter-bed, nearly to the bottom of one of the compartments. The rain-water then has to pass upwards through the filtering material in this compartment over the partition into the second com

partment, and downwards through the filtering material there, into the lower part of that compartment, where there is a tap from which it may be drawn off. An overflow pipe is, of course, provided, so that the water cannot rise above a certain level.

In conclusion, I need not only say that the number of instances in which epidemics of typhoid fever, cholera, and some other diseases, have been traced to the use of impure water, or of milk contaminated with foul water, must make it evident to everyone that it is of the greatest possible importance that we should have uncontaminated sources of water supply.

CHAPTER IV.

REMOVAL OF REFUSE MATTERS.

Dest, KITCHEN REFUSE, EARTH-CLOSETS, &c. CONSERVANCY AND WATER-CARRIAGE SYSTEMS COMPARED.

A very important matter in the sanitary administration of largo towns, and an important matter for the consideration of every householder, is the regular and frequent removal of the house refuse known as " dust." This consists chiefly of ashes and cinders; but unfortunately the dust-bin or ash-pit is only too convenient a receptacle for all kinds of rofuse matters, including kitchen débris, and so, in a large number of instances, these receptacles, especially in hot weather, become excessively foul, and an abominable nuisance. If the dust were removed daily, as it should be wherever this is practicable, the mixture of organic matter with it would not be of great importance, but where this cannot be done, it is very necessary to insist that the dustbin shall be used for nothing but ashes, and that all organic kitchen refuse, such as cabbage leaves and stalks, shall be burnt. This can be done without any nuisance by piling them on the remains of the kitchen fire the last thing at night; thus they are gradually dried during the night, and help to light the fire in the morning. When dust is valuable to those who contract to remove it (for this

work is generally let out to contractors by the parish authorities, although in several instances it is now being done with great advantage and saving to the ratepayers by the parish workmen themselves), there is no difficulty in getting it removed. The contractors are only too glad to get it, and even prosecute people who keep any of it back for their own uses. The cinders and ashes from dustbins are largely used in brickmaking, and so when the building trade is slack dust becomes worthless. The contractors, instead of paying for it, require to be paid considerable sums to take it away, and the less they take away, and the less frequently they call for it, the more advantage do they get out of their bargains. This has been the case for some years, and in one parish alone, that of Islington, where I was formerly Medical Officer of Health, the difference that it made to the sanitary authority in one year as compared with another only six years before, was no less than £6,257; whereas in the former year the sanitary authority received £2,200 from the contractors, in the latter they had to pay £4,057. No doubt the best plan to get rid of such refuse matters would be to put them outside the door early in the morning in a box or bucket, to be called for every morning by the contractor's men, and this is already done in some places. Otherwise it is necessary for every householder to take care that his dustbin does not become a nuisance to himself or his neighbours, from too large an accumulation being allowed to remain in it, or from improper matters being thrown into it. Dust receptacles ought not to be kept inside houses, as

they very frequently are. Neither ought they to be built against the wall of the house, for emanations from them will percolate through the walls into the interior of the house. They ought always to be covered with a sloping roof, so that the rain may run off; if rain water is allowed to get into them, they are much more likely to become a nuisance. Rain-water pipes ought not to be carried through dust-bins, or foul air from the latter will get into the pipe through a leaky joint, or a damaged place, and ascend it, causing a nuisance in one of the upper rooms, or elsewhere. I have known a serious nuisance caused in this way. Portable galvanized iron boxes are much better than built dust-bins, as they can be kept much cleaner.

Removal of Fxcretal Matters by Conservancy Systems.Under these systems the excretal matters are either collected without any admixture, in receptacles known as cesspools, or they are mixed with ashes, and other house refuse, forming what is called a "midden heap," and of these two old plans all the dry closets, pail, and tub systems, &c., may be said to be modifications. Cesspools were formerly largely used, especially for houses built on porous soil. A pit was dug into which the excretal matters were discharged and allowed to percolate away into the soil-frequently into neighbouring wells. Often there was not only no pretence at making this pit impervious, but every facility was given to allow of the percolation of the foul water, &c., into the soil around. Thus the walls (when there were any) were made merely of rough blocks of stone placed one upon nother. In some instances these pits were not opened