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occurred in Paris, which, as just stated, is supplied under this system, and where now, in the heat of summer, with the cholera possibly approaching the town, the drinking water is said to be failing, so that nearly all the supply will have to be taken from the other source, the Seine. Unfortunately, this water is not as carefully filtered and aërated as it would be if it were usually used for domestic purposes, and it may consequently prove a source of danger and disease.

When only one supply exists for domestic purposes, means are generally taken to render it as pure as possible, either by efficient filtration, or by such other means as may be found necessary. Should such water not be considered of a sufficiently high standard of quality, a pure source is selected, and the old one abandoned; when this is impossible, the use of household filters becomes universal.

When the Chelsea Water Company first moved their intake to Ditton, in carrying out the works an extra reservoir was constructed, and extra mains were laid for supplying unfiltered water for road watering and other purposes, but in practice this arrangement was found to be no saving, and to possess no advantage over supplying filtered water for these purposes, so it was discontinued, and now none but filtered water is supplied.

It may be contended that if water were sold by meter, the difficulty of supplying the two kinds of water for domestic purposes would be overcome, inasmuch as the extra cost of the purer water would prevent its excessive use, and so conduce to its conservation and the greater use of the inferior water. This argument, probably, would prove fallacious, as the servants who use the water are unaffected by any such considerations.

It might, further, be urged that the inferior water should only be laid on to the closets, and that the supply to them should be independent of the general domestic supply. This arrangement would leave the remainder of the domestic supply to be furnished by the better water. Baths even would have to be supplied from it, for when it is remembered that they are very frequently supplied with hot water from an apparatus from which water is drawn for other purposes, it will be seen that it would be practicably impossible for them to be connected with an inferior supply. Apart from special cases, in which water is distributed under great pressure for power, and under smaller pressure for ordinary consumption, only one plan of dual supply seems feasible, which, however, from the necessity for duplicate mains, &c., must necessarily be costly, though it might prove advantageous in many respects if carefully worked out. The writer would hesitate to advise such a scheme, except under exceptional circumstances. It is that the domestic supply should be entrusted to a company selling water by meter, and the general supply (including supplies to closets) should be in the hands of the municipal authority, and paid for by a general rate levied on all property. In addition, the municipal authorities would receive payment for any water they might dispose of for manufacturing purposes. It will be seen that, under this arrangement, the municipal authority would have under its control water-works (supplying fairly good water it must always be presumed) for supplying closets, road and public garden watering, sewer flushing, fire extinguishing, and to sell for manufacturing purposes. which supplied water by meter for domestic use, and for those manufacturing purposes for which pure water is indispensable, should also be under the supervision of the municipal authorities.

Such a system as the above would probably only be found worthy of consideration in the case of a town which possessed a supply of good water, but of so limited a quantity that the rapid growth of the city rendered an increased supply indispensable, and where there was an inferior supply near, which could be made available at small cost. By these means the consumption of the pure water would probably be reduced to such an extent as to be available for a much larger population, and at the same time, from the fact of the municipal authorities controlling

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the house drains, closets, and flushing supplies, an improved sanitary condition might result. It is, however, not easy to imagine a town in such a position.

Rain water, as it falls, is in a comparatively pure state, and if proper measures are taken to preserve the surplus falling in wet seasons, and to keep it from contamination, it will generally be found that the rain falling in each watershed is amply sufficient to supply the whole of the inhabitants dwelling in their districts. If any scarcity exists, it is owing, generally speaking, to the want of proper care, or to the fact that the district is so subdivided under different authorities, that joint action for the proper conservation of the rainfall is impossible.

MODE OF DISTRIBUTION, WITH SOME

REMARKS ON DUAL SUPPLY.

By HENRY J. MARTEN, M.Inst.C.E.

UNTIL comparatively recent times no attempts were made to afford what we now term “a domestic supply,” that is to say, a supply of water distributed to and available within each house for general domestic purposes.

The large supplies of fine water introduced into the principal cities of ancient times, by means of the magnificent aqueducts of which there are many remains to this day, were directed, so far as distribution is concerned, to the supply of public baths and fountains, and possibly here and there to the supply, for similar purposes, of a few of the private residences of the wealthy classes.

A house-to-house supply, such as we have in modern times, was unknown and undreamt of. The supply for domestic purposes had to be obtained by the occupants of the houses either from the public fountains, or from the streams flowing from them, or was supplied in detail by VOL. VIII.-H. C.

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water carriers, somewhat after the fashion in which milk is now supplied from house to house. Although, according to Pliny, the ancients were aware that water under pressure rises to the height of its source, little practical advantage was taken of the knowledge of this fact. Water under pressure was occasionally conveyed for some distance through stone or earthenware tubes or in leaden pipes. The two former were, however, difficult to be kept tight, and the latter were not only very expensive, but, at an early period of their history, were found to act deleteriously on the water flowing through them. Although, therefore, immense volumes of water were frequently brought into ancient cities, as into Rome, where, according to Strabo, “whole rivers flowed through the streets,” and where the total quantity so delivered probably exceeded three hundred gallons per diem to each inhabitant, there was practically no distributed domestic supply.

The inhabitants of modern London, therefore, although only furnished with a supply per head equal to one-tenth of that which used to flow into old Rome, are nevertheless infinitely better off than the ancient Roman, because the thirty gallons supplied to the modern Londoner are delivered exactly where he requires it, "upstairs, downstairs, or in my lady's chamber," and the supply is at all times available by the mere turning of a tap. We have here a good illustration showing how various combinations of applied science, united to the practical skill of modern times, have resulted in a tenfold economy, coupled, at a moderate estimate, with a tenfold advantage to the water consumer.

If modern London were supplied in the same wasteful and unscientific manner as ancient Rome, the quantity of water required for the purpose would exceed in volume the average flow of the River Thames at Kingston, and whilst this immense volume of water would be rushing from public fountains, and down open channels made for the purpose in the streets, the inhabitants would be totally without the comfort and advantage which they at present enjoy of a domestic supply delivered under pressure into each of their houses.

Coming to modern times, the distribution of a domestic supply dates back from the time of Peter Morice, who, in 1582, erected waterworks for the supply of the City of London by means of pumps actuated by water-wheels placed in the first two arches of old London Bridge. He appears to have distributed the water under pressure through leaden pipes, but it is probable that a few years later these were replaced by wooden pipes, which, as early as the year 1628, were being laid down by the New River Water Company. These wooden pipes consisted of the trunks of elm trees, cut into lengths and bored longitudinally to an internal diameter of from 6 to 12 inches, in accordance with the internal pressure they were required to withstand. In the parts of the town lying at the lower level (where the pressure would be greatest), the diameter of the bore would be 6 inches, so as to leave a considerable thickness of wood between the inside of the bore and the outside of the tree. In the higher parts of the town, and near the reservoirs, where the pressure would be less, the bore would be gradually increased to 12 inches in diameter, a less thickness of timber being required in those parts. The joints of these wooden pipes were made by forming one end of the tree into a conical shape, and hollowing out the other to correspond ; the several lengths, when laid, being then driven one into the other.

These wooden pipes, however, proved very defective, as the loss by leakage was estimated at not less than onefourth of the whole quantity flowing through them. From decay and other causes they required also to be renewed on the average about once in every twenty years; and consequently, as at one time the New River Company had 400 miles of these pipes laid down, they had to take up and renew upwards of 20 miles in length each year.

Owing also to the small diameter of these wooden pipes, where they had to bear any amount of pressure, more than one line-and in one case no less than nine lines of pipes

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