446 REPORT — 1873. 



tion through the soil, and almost always heated (sometimes considerably so) 

 by surface-flow, as was observed both at Tunbridge WeUs and at Earlswood (the 

 temperature of the effluent water in the latter case being actually 5° F. higher 

 than that of the sewage), in winter, on the other hand, the cooling which takes 

 place is less with percolation thi-ough the soil than with surface-flow in 

 both instances ; so that " these results are favourable to percolation through 

 the soil, as opposed to mere surface-flow, both in summer and winter. Per- 

 colation causes a considerable cooling in the summer, while in winter it does 

 not cool the effluent water so much as surface-flow does." 



These results induced the Committee to make the following distinct state- 

 ment in their Third Report, p. 185 : — " It may seem almost superfluous for 

 the Committee, after so many years of general experience throughout the 

 country, to argue in favour of the subsoil drainage of naturaUy heavy or 

 naturally wet land with impervious subsoil for purposes of ordinary agricul- 

 ture ; but some persons have strongly and repeatedly called in question the 

 necessity of draining land when irrigated with sewage ; and the two farms at 

 Tunbridge Wells, to a great extent, and more especially the Eeigate Farm at 

 Earlswood, have been actually laid ovit for sewage-irrigation on what may be 

 called the ' saturation principle ; ' so that it appears to the Committee dcsi- 

 rp.ble to call attention to the fact, that if drainage is necessary where no 

 water is artificially supplied to the soil, it cannot be less necessary after an 

 addition to the rainfall of 100 or 200 per cent. But a comparison of the 

 analyses of different samples of effluent waters which have been taken by the 

 Committee from open ditches into which effluent water was overflowing off 

 saturated land, and from subsoil-drains into which effluent water was intermit- 

 tently percolating through several feet of soil, suggests grave doubts whether 

 effluent water ought ever to be permitted to escape before it has percolated 

 through the soil." 



At Breton's Farm, where the sewage of the town of Romford, with a popu- 

 lation of 6338 (a little more than two thirds of which only discharge their 

 refuse into the sewers, the previous estimates having been all too high), is 

 utUized upon 121 acres of land, there are special advantages for accurate in- 

 vestigation. The soil, which was very poor, consisting in many parts almost 

 entirely of gravel (as will be seen by the analysis already quoted from the 

 Committee's Second Report), was laid out in rectangular beds on the Ridge- 

 and-Furrow System, the " beds " or "lands," each 30 feet in width, running at 

 right angles to the main carriers which distribute the sewage. The sewage, 

 when it arrives on the farm, is received in one of two tanks, where a deposit 

 takes place and a scum forms on the surface. The liquid is run out between 

 these into the pumping-weU, and is raised by a pump " to a height of about 

 25 feet into iron troughs supported on wooden tressels, which convey the 

 sewage to all parts of the farm, by discharging it either directly into the gut- 

 ters or grips formed on the ridges of the ' lands,' and out of which the 

 sewage is distributed right and left down the slightly inclined slopes of the 

 lands, or, in the first instance, [into concrete carriers, raised by earth banks 

 to a height intermediate between the height of the iron troughs and the 

 level of the ground." (Report II. p. 62.) "About 85 acres of the farm, 

 which are above the level of the tank, have been underdrained by pipe-drains 

 50 yards apart, and from 5 to 6 feet in depth, in such a manner that the water 

 from the drains can be discharged into the sewage-tank if required in dry 

 weather, or at pleasure into the river Rom." 



This arrangement afforded excellent opportunities for the gauging of the 

 effluent water. 



