CHAPTER III.

Conservancy or Dry Systems.

By this title is understood the collection of the dejecta unmixed with water, and either its direct application to garden or other land, such as is usually done in rural districts, or its reception into moveable pails for collection twice or thrice a week, the moveable pails at each house being replaced by empty ones, the contents of the full ones being conveyed to a depôt, there to be dealt with, as notice shortly, for conversion into manure.

Midden Privies-Rural Districts.

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In country districts, in the absence of any sewerage system, middens are very common. That it is an insanitary method need scarcely be remarked, and but few words need be devoted to it.

In the curtilage of many a rural cottage the midden is frequently of very unsatisfactory construction, and consequently its contents may percolate into the surrounding soil, with the possibility of contaminating the water supplying a neighbouring well; and, if not, it may possibly vitiate the air in the vicinity and form a breeding ground for flies, now known to be the carriers of many disease germs. Also, it may only be emptied at infrequent intervals, and even allowed to overflow, thus becoming a danger to the health of the residents of the vicinity.

Middens are emptied in two or three ways. A simple, if crude, method is by the use of a ladle. In another, some kind of pump is used. Of the latter there are several useful kinds. Chain pumps which have no valves are most suitable, as they will pump thick liquids.

Midden Privies in Towns.

It was many years, from the time when middens were first used in towns, before their connection with the causation of epidemics of various air and water-borne infectious diseases was understood. This was because the science of epidemiology was practically unknown, and the connection of such diseases with their specific organisms was therefore quite

unappreciated. It was many years after before any real steps were taken to do away with these insanitary privies in populous centres, and to employ earth-closets in their place. The change was, however, by no means as satisfactory, sanitarily, as its advocates anticipated.

In this connection it will be sufficient to quote from the experiences of Leicester and Nottingham. The latter city is now one of the rapidly decreasing number of large towns which still, to a very large extent, employ conservancy systems for dealing with the night soil. Leicester and Nottingham are towns in many respects possessing similar features. The former has, however, adopted water-carriage for its sewage in lieu of pail-closets; and it is instructive in this connection to compare the death rate from enteric fever in the two towns.

In 1908, for instance, the death rate in the former was three, whilst in the latter it was eleven per 1000. In the previous ten years the rate was eight and twenty-four respectively. In Nottingham, also, the death rate from the same infectious disease, according to a report of the Medical Officer of Health, in pail and midden closet-houses, as compared with those provided with water-closets, shows a higher incidence, as the following respective figures for 1908 reveal:

I case in every 185 houses supplied with pail-closets

An improvement on the midden privy is what is known as the pail-closet. The earliest of this class was that invented by the Rev. J. M. Moule. Improvements of the same kind of pail are still on the market. This class of pail is usually of galvanised iron.

Fig. 1 illustrates the simplest and cheapest form of pail. It ought to be provided with a tight-fitting lid. Dry earth should preferably be provided in a receptacle in the closet building, and applied to the pail by means of a shovel after each usage, as it helps to deodorise the fæcal matter, and absorb the greater part of the moisture. Besides this method. of application by hand, the earth can also be applied automatically from a receptable at the back in the case of a selfacting earth-closet (Fig. 2), with a moveable pail underneath

the seat for the reception of the dejecta, and actuated by the movement of the person using it ; or in a "pull out pattern

(Fig. 3), by means of a handle and lever in the earthcontainer.

The self-acting earth-closet of the British Sanitary Co. (Fig. 4) is on similar lines to Fig. 2. By it, when the seat is relieved after use, the weight of the lever brings out the

case which are either much modified or are totally different in character to those prevailing in another.*

Although the conditions may be similar at the outset, although, indeed, the crude sewage to be dealt with in one district may be identical in composition with that in another, yet the method of treatment which gave satisfaction in the one case may be most unsuited to the other. This may be due to a variety of reasons, some of which are understood, whilst others still await elucidation. Difference in the nature of the water supply, in dealing with water-borne sewage, or slight differences in climate, or in physical environment, will be, in most instances, sufficient to render a method of treatment suited to one district inoperative in another.

Again, a slight difference in the chemical constituents of a particular water-borne sewage, due to the admission thereto, for instance, of liquid wastes from a brewery, or tannery, or manufacturing process, will probably call for some modification in the method of treatment, before it can be considered to have been satisfactorily dealt with.

Another factor, which has to be considered in the working of every installation, is the change which takes place both in constituents, volume and quality of the sewage to be disposed fin almost every hour of the day.

In installations connected with small detect the difference in the com the local washing-day, when als and fats which are used ake femselves nd interfe

Now,

their toll of lives in one part of the country or another. although not yet quite things of the past, as the typhoid epidemics at Maidstone, Gloucester, and Lincoln within recent years have shown, their virulence is much less in comparison.

The decrease in the death-rate furnishes ample evidence of the value of the advance which sanitary science has made during the intervening years, and the advance in the science of sewage treatment and disposal has played no mean part therein.