By Mr. J. GORDON, C.E.

The average mortality for England and Wales was 22.4 in 1838, and in 1886 19.3, which shows a saving on last year's population of England and Wales of 86,400 lives annually, and a saving in suffering from an estimated number of about 1,728,000 cases of sickness. To accomplish all this, vast sums of money have been expended, probably not always wisely, inasmuch as there have been mistakes made in this direction, as in all new developments of science when applied in practice, and evils have arisen which, if foreseen at all at the outset, were underrated.

The great object of the public health act, 1848, was to enable local authorities by its adoption to properly sewer, drain, and cleanse their towns, and to provide efficient supplies of water, free from contamination and impurities dangerous to health. The raising of money by loans repayable in a series of years, which the act empowered, enabled all these objects to be accomplished, and, while the first duty of local authorities was undoubtedly the provision of a good supply of water and proper sewerage for the removal of liquid filth from the immediate vicinity of inhabited dwellings, the carrying out of proper works for the latter object has been of much slower growth than the former. Private companies led the way, in fact, in providing supplies of water, inasmuch as there was a prospect of the works becoming remunerative to shareholders investing their money in them; and in nearly every instance where local authorities have eventually found it to be in the interests of the inhabitants of their districts to purchase the work, they have had to pay high prices for the undertaking.

This has generally led to a great deal of dissatisfaction with companies holding such works, but it must not be forgotten that the companies would, in most instances, never have had any existence if the local authorities had taken the initiative, and that but for the companies this great boon of a pure supply of water would most probably have been long delayed to many large as well as small communities.

The evils which have arisen from the sewering and draining of towns have been of a twofold character. First, in the increased pollution of rivers and streams into which the sewage, in the earlier stages of these works, was poured without any previous treatment; and secondly, in the production of sewer gas, which up to the present moment seems so difficult to deal with. These concomitant evils and difficulties attending the execution of sanitary works are in no way to be underrated, but it still remains the first duty of town authorities to remove, as quickly as possible, all liquid and other refuse from the midst and immediate vicinity of large populations, before putrefaction has had time to take place.

There are some minds whose course of reasoning seems to lead them to the conclusion that the evils attending the introduction of modern systems of sewerage are greater than those of the old methods of dealing with town sewage and refuse, but the facts are against them to such an extent that it would be difficult to point to a responsible medical officer in the kingdom who would be courageous enough to advocate a return to the old regime of cesspools, privy ashpits, open ditches, and flat bottomed culverts. The introduction of earth closets as one of the safeguards against sewer gas has made no headway for large populations, and is beset with practical difficulties.

In the Midland and Lancashire towns the system known as the pail or tub system has been much more largely introduced as a substitute for the water closet, and it has, from a landlord's point of view, many attractions. In the first place, the first cost, as compared with that of a water closet, is very small, and the landlord is relieved for ever afterward I believe, in most towns, of all future costs and maintenance; whereas, in the case of water closets, there is undoubtedly great difficulty in cottage property in keeping them in good working order, especially during the frosts of winter. There are, however, many objections to the pail system, which it is not proposed to touch upon in this address, beyond this, that it appears to be a costly appendage to the water carriage system, without the expected corresponding advantage of relieving the municipal authorities of any of the difficulties of river pollution, inasmuch as the remaining liquid refuse of the town has still to be dealt with by the modern systems of precipitation or irrigation, at practically the same cost as would have been the case if the water carriage system had been adopted in its entirety.

The rivers pollution act gave an impetus to works for the treatment of sewage, although much had been done prior to that, and Leicester was one of those towns which led the way so early as 1854 in precipitating the solids of the sewage before allowing it to enter the river. The innumerable methods which have since then been tried, and after large expenditures of money have proved to be failures, show the difficulties of the question.

On the whole, however, sewage farms, or a combination of the chemical system with irrigation or intermittent filtration, have been the most successful, so that the first evil to which the cleansing of towns by the increased pollution of rivers gave rise may now be said to be capable of satisfactory solution, notwithstanding that the old battle of the systems of precipitation versus application of sewage to land still wages whenever opportunity occurs.

The second evil to which I have made reference, viz., that of sewer ventilation, seems still unsolved, and I would earnestly entreat members, all of whom have more or less opportunities of experimenting and making observations of the behavior of sewer gas under certain conditions, to direct their attention to this subject. It is admitted on all hands that the sewers must be ventilated - that is, that there must be a means of escape for the polluted air of the sewers; for it is well known that the conditions prevailing within the sewers during the twenty-four hours of the day are very varying, and on this subject the early observations of the late medical officer for the City of London (Dr. Letheby), and the present engineer for the City of London (Lieutenant-Colonel Heywood), and the still more recent investigations of Professor Pettenkofer, of Munich, Professor Soyka, of Prague, and our own members, Mr. McKie, of Carlisle, Mr. Read, of Gloucester, and others, are worthy of attention. It does not, however, seem to be so readily or universally conceded that a plentiful supply of fresh air is of equal importance, and that the great aim and object of sewer ventilation should be the introduction of atmospheric air for the purpose of diluting and oxidizing the air of the sewers, and the creation of a current to some exit, which shall, if possible, either be above the roofs of the houses, or, still better, to some point where the sewer gas can be cremated.