The Commissioners appointed to inquire into the best means Sewage of preventing the pollution of rivers, in their first Report irrigation. (Session 1866, p. 12), say with regard to sewage irrigation :

"Sewage Irrigation.-The Commissioners appointed to 'inquire into the best mode of distributing the sewage of towns, and applying it to beneficial and profitable uses,' in their third and final Report delivered in the month of March last year, expressed as the conclusion to which they had unanimously come, after an investigation extending over eight years, that The right way to dispose of town sewage is to apply it continuously to land, and that it is only by such application that the pollution of rivers can be avoided.

"Fully concurring with this conclusion, we have not reopened the consideration of the numerous and diverse expedients for the disposal of town sewage (though with respect to none of them have we declined to receive such evidence as has been tendered to us), but we have thought we should best fulfil our instructions by restricting ourselves to the inquiry whether the absolute prohibition of discharge of sewage into rivers, or the absolute compulsion of town authorities to apply it to the land, would result in injury to health or entail other inconvenience.

"All expedients for disposal of town sewage otherwise than by application to land, seem to us on one ground or another objectionable. Cesspits in towns corrupt the air and corrupt well-water; they are incompatible with public health, and should be abolished. Sewerage has therefore become a necessity for any large community. The difficulty is to deal with the volume of sewage thus concentrated, so as not to cause a nuisance either in the atmosphere or in rivers. Disinfectants and filtration have been tried in many forms, but without success. As applied to sewage, disinfectants do not disinfect, and filter beds do not filter. Both attempts have been costly failures. The Local Board of Health at Croydon at one time were spending large sums annually on chemical and mechanical experiments to no purpose, but to expose themselves to law-suits; they then commenced the process of sewage irrigation.

"In order to fully ascertain the effects upon health of sewage irrigation, we have visited the principle places at which that process is carried on, viz. :-Croydon, Norwood, Worthing, Carlisle, Edinburgh.

"We also held open public inquiries at Worthing, Croydon, and Norwood.

"At Worthing we found the Sewage works, which have now been in operation for more than a year, unobjectionable. Not a single case of sickness was attributed to the irrigation. With regard to Croydon, the inhabitants of that town generally cannot suffer from their irrigation fields, the sewage farm at Beddington being at a distance of about three miles from the town.

Sewage irrigation.

At the public inquiry, all the witnesses, medical gentlemen and others, were agreed that the irrigation works were not injurious, to health. As to the irrigation works at Norwood, no complaints have been made by the persons representing that district upon the Local Board of Health at Croydon, and the general rate of mortality in Norwood is low. Some dissatisfaction, however, is felt by one or two proprietors and occupants of house property in the immediate neighbourhood of the works; and Dr. Cresswell, one of the local practitioners, stated that the question had occurred to him as one worthy of investigation, whether certain peculiar cases of illness, resembling ague, which he had met with in the district, might not have been caused by miasma from the irrigated fields. The works are inconveniently near to the outskirts of the town, and may exercise a depreciatory influence on the value of adjoining houses; but, on the whole, we are satisfied that no ground exists for serious apprehension of miasma from fields irrigated with sewage.

"If sewage irrigation had really bred a special class of diseases, it would hardly have been tolerated for two centuries on so vast a scale near Edinburgh.

"It is necessary not to mistake instances of abuse for defects in the system of sewage irrigation. Sewage, if fresh, and in the open air, is scarcely perceptible to the smell. If sewage

be pent up in sewers and discharged on the land in a state of active putrescence; or if, as took place once at Norwood, the depositing tank is allowed to get out of order; or if, as at Edinburgh, the carriers are so rudely constructed and so neglected as to become reservoirs of stagnant sewage and accumulating places of corrupt sewage deposit, unpleasant, if not mischievous consequences must be expected; but these are cases of abuse, preventable by common care.

"Sewage water, if passed over a sufficient area of grass land, passes off bright, tasteless, and without smell. At Croydon, ever since the town was sewered (about the year 1852), the sewage of about 17,000 of the inhabitants has been discharged into the river Wandle, a clear trout stream which breaks out from the chalk above the town and flows, as ornamental water, through residential properties. For fouling this stream the Local Board of Health, so long as they resorted to chemicals to purify their sewage, were exposed to continual litigation. They then commenced the irrigation process upon land at Beddington, and discharged the effluent water from their irrigated fields into the Wandle. Mr. Gurney, finding a dearth of water at his mills, applied to the Local Board for leave to bring the affluent water from the sewaged fields into the Wandle at a point above his mills; and having obtained leave, formed at his own expense a conduit of considerable length, whereby the effluent water is now conducted through his grounds by the side of his carriage drive into the river as it

flows through his estate. It appears, from the evidence both Sewage of Mr. Gurney and of his agent Mr. Reynolds, who resides irrigation. upon the estate close to the outfall at Beddington, that there is still occasional cause to complain of the condition of the effluent water, as it sometimes comes off the land either turbid or so imperfectly cleansed from sewage, that it pollutes both the river Wandle and the atmosphere in the vicinity. These evils, so far as they exist, we are satisfied admit of explanation. When the water is turbid (as distinct from being foul from sewage), the cause probably is, as suggested by Mr. Gurney, that cattle sent in to graze upon the irrigated fields (a very large number in proportion to the acreage), have trodden the surface and fouled it with their dung. When the effluent water flows off, carrying both to sight and smell unmistakeable signs of sewage, it has not been applied to a sufficient area of land. The smell has been found most objectionable on Sunday evenings, probably, because the men have on those days neglected to do the amount of work necessary to effect a proper distribution of the sewage. Mr. Reynolds expressly states that the grievance is only occasional; that at other times the water comes down as pure to look at as he could desire, as pure as the river water; that he has no fault to find with sewage irrigation if properly managed; that, on the contrary, he believes it to be a great principle, and thinks it a pity that it should be called in question through the neglect of those who conduct the works. If at any time Mr. Gurney finds the effluent water objectionable, he has only to close his conduit and keep the water out. This hitherto he has not done.

"Sewage irrigation requires to be undertaken and conducted with strict attention; the site must not be too near to dwellings, adjoining wells should be watched, and if the soil be very porous, disused; the sewage must be applied fresh, and over a sufficient area of land. If these conditions are observed, irrigation will be found to be the mode of dealing with sewage which results in the largest amount of good to the land and the smallest amount of harm to flowing water.

"There may be difficulty in some cases in finding land available for sewage irrigation, but, with the exception of lands liable to be flooded, there seems to be no soil that will not serve the purpose. Between the light and blowing sands of Edinburgh and the stiff clay of South Norwood are included all the mechanical differences of soil which can be met with in this country, but at both extremes we find the application of sewage attended with success. In some respects, indeed, a heavy clay is even more suitable than lighter soils; from its very nature it is more productive of healthy vegetation; and from its well-known chemical properties, it is more effective in the purification of sewage.

The same land will serve the purpose of sewage irrigation

K

Sewage

irrigation.

continuously. The process to the soil is one not of exhaustion, but of constant renovation. Part of the Craigentinny meadows has been continuously irrigated for two centuries. Sewage can be pumped any height, and carried any distance. Its conveyance therefore to a given point is merely a matter of cost. There is no real difficulty in dealing with sewage, whether the volume be, as at Norwood, a few gallons per head, or, as we are informed that it is at Croydon, from two to four times as great as the water supply of that town. On a clay soil (or wherever pumping is necessary) it is desirable to restrict the dilution. On a gravelly porous soil, on the contrary, as shown by Mr. Marriage, it is an advantage that the sewage should be largely diluted, since it is then much more readily distributed over the surface.

"If a farm be large enough, there is no time when some portion of the land may not be capable of receiving the sewage. The process of irrigation may go on day and night, in wet and drought, in summer and in winter. At Croydon where advantage is taken of gravitation, the sewage (though varying in volume at different hours) does run upon the land unintermittently, 'continuous as time itself.' This is a matter of first importance, regard being had to the necessity that sewage, as soon as produced, should be removed from the town and be applied whilst fresh.

"The powers which towns now possess for the purposes of applying their sewage to land are contained in-Public Health Act 1848, 11 & 12 Vict. c. 63, ss. 45, 46, 84; Local Government Act, 1858, 21 & 22 Vict. c. 98, ss. 30, 68–75; Local Government Amendment Act, 1861, 24 & 25 Vict. c. 61, ss. 4-7; Sewage Utilization Act, 1865, 28 & 29 Vict. c. 75,; Land Improvement Act, 1864, 27 & 28 Vict. c. 114.

"The cost to a town of sewage irrigation depends upon the balance of Expenditure and profit. This must vary in different places.

"In the selection of a site for irrigation due regard should be had to economical considerations. The cost of conveying the sewage depends partly upon the distance, but still more upon the height to which it is to be pumped, the volume to be pumped, and the price of coal. Laying main pipes an additional length of a mile or two through open country involves an outlay, the interest of which may be trifling as compared with the annual expense of pumping. Unless, therefore, there is much difference in the price of land, it would be cheaper to let the sewage flow by its own gravity a distance down the valley, than to pump it to an adjoining upland. But saving in the first cost of land may be more than a set-off against the expense of additional piping and of pumping even to a considerable height. If all the land in the immediate neighbourhood of a town is building land, and none is to be had except for an inordinate price, the circumstance need create no difficulty; it will only

be necessary to go further for a site where land is to be had at Sewage a lower value. The Croydon Local Board of Health, as would irrigation. appear from the evidence of their chairman and their engineer, are prepared, in the event of their being refused a renewal (on reasonable terms) of their present lease of Beddington Farm, to pump their sewage to an elevation of 150 feet, so as to command land at a distance.

"It is not necessary that the cost of preparing the land for sewage irrigation should be great. The carriers and distributing branches, whether made as open trenches or of earthenware or cast-iron piping, need not be costly. Whether the liquid is pumped or flows to its destination, its distribution over the land should always be effected by gravity.

'Filtration,' in the sense in which the term is used of filtering water for domestic uses, is not applicable to sewage. Town sewage cannot be filtered through an ordinary sand filter, either by the downward or upward process; nor is it necessary in any case to attempt this form of filtration for sewage. Mechanical deposition and separation of grit and flocculent matter are alone required, and these operations can best be performed in open canal-like tanks.

"Fields irrigated with sewage can be used for horses and milch cows to graze upon, and will fatten cattle and sheep. But there are practical objections to such use. Cattle grazing in a sewaged field, tread the surface and foul it with their dung, and are apt also to tread down the banks of the sewage-carriers, and thereby to foul the effluent water. Dung, so applied, is not required for manure by the owner of a sewage farm. Sewage fields will yield wholesome hay; but in this uncertain climate there would be great difficulty in making hay from crops of grass so heavy. Where irrigation is carried on upon a large scale, if the crops are to be converted into hay, probably some artificial process of haymaking will be required. "The most profitable course is, we believe, to sow Italian rye grass, and to sell the crop fresh cut as food for horses and cows. A field will in the year produce four or five crops, each of extraordinary weight. How often the grass should be resown depends upon a balance of considerations. Crops from the same seed annually deteriorate; on the other hand, to break up the soil involves temporary suspension of crops, additional labour, and other expenses. At Norwood, where sewage operations commenced only a year ago (1865), the tenant has already over part of the farm had crops of 50 tons per acre, and expects in the ensuing year to obtain about 50 tons per acre uniformly over the whole. At Edinburgh, the strips of irrigated land are let yearly at public roup, and fetch from £20 to £40 per Scotch acre. At Croydon the meadows are equally productive. At Worthing part of the sewage from a population of about 9000 persons was applied last year (1865) to 25 acres of land. The value received for the produce was £645, or about £25 16s. per