20 feet above the roof of the highest house supplied from it. Fire outlets ought to be readily accessible from the roadway or pavement, and have signplates fixed to the walls opposite. When a distributing pipe is laid expressly to provide water to extinguish fire, it ought to be placed at a distance from the buildings, in order that there may be safe access to the hydrants when the fire breaks out. means em The impurities of water are of two kinds-those held me- Impurities of chanically in suspension, and those in solution. Of the former, water, and the the heavier parts are got rid of in the reservoirs as deposit, and the lighter parts afterwards by filtering. Filter beds are remove them. ployed to small reservoirs partially filled with layers of sand and gravel, with drain pipes at the bottom. The impurities held in solution can only be removed by distillation, or by a chemical process. The only chemical process to which supply water has as yet been subjected on a large scale is that called "Dr. Clark's process." It is employed to remove bicarbonate of lime from water gathered on the chalk districts. For trade and domestic purposes other than drinking, the water that approaches nearest to perfect purity is the best. Such is the water collected from house-tops in country places, and from gathering-grounds in districts where granite, gneiss, and slate prevail. For drinking purposes, water with a slight admixture of earthy salts is sometimes preferred. Water is said to be hard or soft according to the quantity of Hardness. soap required with it to produce a permanent lather. The matter held in suspension by surface water is for the Surface water most part organic. To prevent its hurtful decomposition store and well reservoirs ought to be stocked with fish. Water from wells water. and springs, on account of the thorough filtering process undergone, is free from organic matter; but holds in lieu of it a quantity of earthy salts, which sometimes, if not removed, renders the water unfit for all trade and domestic purposes. channels. In a system of drainage channels, the sectional area and in- Discharge in clination must everywhere be capable of maintaining the dis- a system of charge arising from the maximum flow into the inlets up drainage stream. The quantity that may have to pass an inlet in a given time depends upon the rapidity of the rainfall on the area commanded, and upon what intervenes between the inlet and the gathering surface. In a system of channels for draining land, for example, where the water to reach the inlet has to find its way through the soil, the soil acts as a reservoir, and the flow at the inlet is less rapid than the rainfall. From the paved and macadamised surfaces of a town, on the other hand, the water flows, or ought to flow, into the drains nearly as fast as it is delivered on the surfaces. A river which has to be provided with reservoirs to prevent Inefficient periodical inundations, is an inefficient natural drainage chan- natural drainnel. Such rivers are sometimes made safe without reservoirs, age. by embanking their sides in the districts liable to be flooded. Discharge in a system for town drain age. Sewers. Branch drains. Connection to surface and house drains. Syphon trap. Outfall of the drainage system of a town. In this state, however, they do not serve as permanent drainage channels to the district shut out by the embankments. The water from the excluded lands is received in canals at the foot of the embankment slopes, and emptied into the river when the floods abate through flood-gates, or through pipes with flap valves opening to the river. In a town drainage-works the discharge to be provided for is the greatest hourly rainfall on the area, and the greatest hourly supply from other sources. The depth of the greatest hourly fall is usually taken at one inch. The main drains or sewers are in general covered conduits at an actual declivity, built of stone or brick in cement, on a base of hydraulic concrete. The cross section ought to be oval or egg-shaped, with the small end downwards. All sewers ought to have a width of at least two feet, so that a man may have access. The foul gas ought to be carried away in pipes to existing chimneys, or to chimneys built on purpose. The required draught may be maintained in the latter by means of a small furnace, or the foul air may be propelled into them by a blowing apparatus like a centrifugal pump, fitted on the conducting tube. Grated openings, with flap valves opening inwards to the sewer, must be provided for the admission of fresh air; also shafts and passages with close doors for access. As in other water channels, the declivities and sectional areas of sewers ought to be arranged so as to keep the velocity of the current as far as possible between the limits of four feet and one foot per second. The smaller branch drains may be close channels made of earthenware pipes. Being inaccessible, they ought to be laid at such declivities as will ensure the maximum velocity of four feet per second in order to prevent the formation of deposit. Surface drains or gutters communicate with the underground drains by what are called gulley holes, covered with gratings, and with syphon traps at the bottom to prevent the escape of foul air. House drains ought to lead directly to the sewer or branch drain without the intervention of a cesspool, which is a convenient means of attaching drains, but highly objectionable in other respects. The syphon trap is simply a pipe with a double bend in it, laid so that water may rest in the U-shaped part. To ensure the efficiency of these as a means of preventing the escape of foul air, it is essential that the pressure in the sewer should not within certain limits be allowed to exceed or fall short of the pressure of the atmosphere. The water draining from towns has its final outfall in the sea, like all other water, and its natural course thither when the town is inland is by the river of the catchment basin in which the town is situated. The proportion borne by the sewage water of a populous district to the uncontaminated river water, however, may be so great that the conveyance in the natural channel of the sewage as it leaves the drains is an water. The insoluble ingredients and the soluble ingredients in Purification excess of saturation are got rid of by allowing the sewage of sewage water to settle, and by filtering it in reservoirs to which the sewer acts as bye-wash. A more complete purification is effected by making the sewer diverge into an irrigation system, where the soil and configuration are suitable. This involves chemical decomposition of the salts in solution. In an extended sewer it may be necessary, either for Extended economy of first cost or to prevent silting up, to bring the sewer. down-stream end of the conduit below high or low water mark. In this case the sewage is received in a reservoir and delivered through flood-gates or by pumping. When the discharge of untreated sewage into the natural Purification channel is interdicted, whether it is more economical to inter- and extension. cept the contaminating matter or to conduct the sewage to the sea, depends upon the position of the drainage ground, the cost of extraction, and the market value of the product. CHAPTER II. SEWERAGE OF DISTRICT. Map exhibiting system of sewerage. 11 & 12 Vict. c. 63, ss. 41, 42. § 1. PUBLIC SEWERS. THIS chapter has reference to sewers which are under the jurisdiction of the Local Board of Health. The local authority under the Sewage Utilization Act, 1865, as it applies to England, and as amended by subsequent Acts. Their powers and duties are treated of in the Fifth Part of this work. With regard to sewerage, the first duty of a Local Board of Health is to cause to be prepared, at the cost of the general district rates, a map exhibiting a system of sewerage for effectually draining their district for the purposes of the Act, upon a scale such as may be prescribed by them, which map is to be kept at the office of the Board, and be open to the inspection of the ratepayers of the district to which it applies at all reasonable times. In their Third Report, the Commissioners appointed to inquire into the best means of preventing the pollution of rivers state that "the sewering of towns is a complex question, and requires to be specially studied so as to effect the greatest amount of good at the least risk of polluting watercourses; natural streams, as small brooks, should not be arched over and formed into sewers, neither should rivers be made the receptacles of sewage. The largest proportion of rain-water may in all cases be turned over the surface into the natural streams; it will not be necessary to form duplicate systems of sewers and drains, but it will require intelligent and careful attention to preserve surface gradients and natural outlets for storm waters, and, where these have been tampered with, to restore and improve them. The sewers and drains of a town should provide for the removal of subsoil water, the slop and waste water from houses, and the contents of water-closets; these sewers and drains may have storm overflows in connection with the natural streams of the district, so arranged as to prevent flooding of houses or bursting of the sewers during thunderstorms. All dry-weather-sewage and such portion of the surface water due to moderate falls of rain as finds its way to the sewers, will flow down with the sewage to the outlet, and be a manageable volume either to apply by gravity, or to be pumped to land for agricultural uses. The remark may be made that, when the sewers overflow, the streams will be polluted; this is true, but the pollution will be a minimum ; the sewage will be in extreme dilution, and the natural streams of the district will be in flood, and most probably muddy by grit and silt washed in from road surfaces, and by fine particles of soil from the banks and surfaces of the land. Floods caused by heavy rains ever have been turbid, and ever will be turbid.” Board has 29 & 30 Vict. c. 90, s. 49. It should be borne in mind that, by the Sanitary Act, 1866, Mode of it is enacted that where complaint is made to the Local proceeding Government Board that a Local Board of Health has made where Local default in providing its district with sufficient sewers, or in the made default maintenance of existing sewers, or that a Local Board has in providing made default in enforcing the provisions of the Local Govern- sufficient ment Act, the Local Government Board, if satisfied after due sewers. inquiry made by them that the Local Board has been guilty of the alleged default, shall make an order limiting a time for the performance of its duty in the matter of the complaint. If such duty is not performed by the time limited in the order, the Local Government Board shall appoint some person to perform the same, and shall by order direct that the expenses of performing the same, together with a reasonable remuneration to the person appointed for superintending such performance, and amounting to a sum specified in the order, together with the costs of the proceedings, shall be paid by the Local Board. Any order made for the payment of such costs and expenses may be removed into the Court of Queen's Bench, and be enforced in the same manner as if the same were an order of such Court. By a subsequent Act the Local Government Board may 32 & 33 Vict. from time to time by order under their hand change the person c. 100, § 8. appointed by them to perform the duty of a defaulting Local Authority. With regard to an order of the Secretary of State under 29 & 30 Vict. c. 90, § 49, the following unreported case may here be cited. Court of Queen's Bench, November 25th, 1870. The Town Council of Darlington v. The Secretary of State. (Before Lord Chief Justice COCKBURN, and Justices LUSH and HANNEN.) THIS was a rule calling upon the Home Secretary to shew cause why a writ of certiorari should not issue for the purpose of bringing up, to be quashed, an order made by the Secretary of State, under the 49th section of the Sanitary Act, 1866. The order, after stating that complaint had been made to the Secretary of State, that the Town Council had made default in providing a proper sewage outfall and means of sewage disposal, and that an inquiry had been held, ordered "That the time within which the Town Council of Darlington shall set about the performance of its duty in the matter of the said complaint, by furnishing me with a plan and "estimate for effecting this object and acquiring either by com |