ISJO.] 



THK CIVIL ENGINEER AND AUCHITECTS JOUUNAL. 



393 



The water-supply of Farnham being ilerivtd from t!;e hill on the south 

 side of which the village stands, I bent my first steps thither, not only to 

 examine its source, as likely to present indications for purity to he looked for 

 elsewhere, but also to have a good bird's-eye view of the whole area under 

 investigatinii. The position of the hill in the south-west, its elevation of 

 nearly 700 feet above the level of the sea, and 300 feet above the plains 

 beneath, admirably adapted it to this purpose. It was then only I dis- 

 covered that the Farnham water does not come from the surface drainage, 

 but is derived from sixteen small springs, issuing at the south side, on a 

 contour, so to say, about 50 feet above the higlies"t level of the hill. From 

 the contracted area out of which so large a supply is gained, I was induced 

 to suspect that tliese springs are not due to the rain.fall on the ground above 

 them. I was further led to this consideration by observini; that, from the 

 slope of the ground, and from the almost impenetrable 'hardness of the 

 superficial covering of gravel, the rain-fall coultl scarcely find its way 

 through this surface. A violent storm having most opportunely come on 

 whilst speculating over this probability, I perceived that the whole of the 

 water apparently ran rapidly down the hill-sides and was speedily out of 

 sight, leaving the surface perfectly dry, except where irregularities retained 

 a tew pools, which subsequent observation proved to me were exhausted by 

 evaporation rather than by percolation, I then examined the north side, 

 and found that on the same contour a still greater indication of springs 

 existed. This satisfied me that these waters are due chiefly to rain-fall else- 

 where; for a rough calculation of the yield of the springs much exceeded 

 the available rain-fall on the area within the contour. 



Convinced of this, I naturally concluded that, if the other ranges of 

 the district \vere of like geological formation, they would in all probability 

 present similar appearances about the same level'; a most desirable source 

 for the streams of tlie country, the advantage of which, in addition to the 

 proposed drainage supply, could hardly he over-estimated. The first week of 

 my researches was confined, therefore, to the nature of the soil throughout 

 the district, presenting generally a vast depth of pure sands, obscured in 

 the higher levels by extensive patches of gravel from 2 to 20 feet in depth ; 

 in the lower, by a poor loam, from one to three feet deep. Patches of peat, 

 here and there in spots of some depth, exist principally in the lower levels. 

 On the west and south-west the loam has a subsoil of very stifl" clay, appa- 

 rently of the London formation, which also crops out on the north side of 

 Farnhamhill. On the north and north-west, in the valleys, there exists 

 within a small area a considerable quantity of iron in some of the peaty 

 bogs. All these are marked upon the plan which I shall hereafter have the 

 honour to lay before the Board, and which I have prepared as accurately as 

 the shortness of time allowed. 



The next object of my research was the quality and quantity of the water- 

 The Board, in their report, have given the quantity now brought into Lon- 

 don by the different water companies as a stream 9 feet wide and 3 feet 

 deep, flowing with a velocity of two miles an hour; a supply double the 

 actual consumption. In the "course of my exploration I could nut fail to 

 observe that such a volume of water of any quality was nowhere to be seen, 

 which at first rather damped my hopes for the future ; hut i remembered 

 that such a body might be made up by collecting the smallest threads of 

 rivulets, and went on my way. To effect this then was my object. 



A most minute inspection of the gathering grounds has shown me that 

 their nature exactly adapts them for the means of collection proposed by 

 the Board, namely, a system of thorough drainage. A more admirable plan 

 of gathering rain-fall could not have been conceived; the sands, acting as 

 a natural filter, deprive the water on its passage to the pipes of anv impurity 

 contracted either in the air or in percolating through the upper'crust ; as', 

 tor instance, where the water might be discoloured by peat, experiments 

 have proved that ihe sands restore its primitive colour, and deprive it also 

 of the flavour imparted by the peat. The heath, which covers the entire 

 area of the gathering-grounds, also stains the water, but the impurity is 

 removed by this process of natural filtration. I would remark, that the dis- 

 colouration visible in the stream called the Ulackwater,is not caused by peat, 

 but by the heath and loose black loamy nature of the soil through wl'dch it 

 flows. This I have proved, by following np its various sources, one of which 

 only, at Cove, passes over peat. Samples of springs rising in peaty hogs, 

 show no discolouration whatever, but are as clear as water issuiuE from 

 sands. 



Remembering Farnham-hill, I turned my attention to look for springs, 

 and, after much and close examination, came to the conclusion (hat the 

 origin of many little silver threads of water, silently stealing down the hill 

 sides under the grass, arose also from such sources. A diligent search 

 showed me that the quantity of water to be derived in this manner within 

 the original area of the gathering-grounds is so great, that if the neighbour- 

 ing ranges of mountains and hills on the soulh side— namely, Ilindhead, 

 blackdown, Hascombe-hills, Leithhill, &c., presented the sa'me feature, I 

 might probably hope to collect a stream 9 feet wide and 3 feet deep, of the 

 desired softness and purity. 



I am now happy to inform the Board, that a month's researches into 

 every hill and glen, every copse and crevice, has produced this result, 

 leaving tested the waters as they issue from their sources, I can announce 

 that I have gauged a sufficient number of springs and rivulets to enable me 

 to form an opinion both as to quantity and quality; the water being of its 

 primitive purity, perfect as to aeration, brilliant in colour, soft alniost as 



distilled water, of a grateful temperature, about 50', and almost free from 

 all mineral, animal, and vegetable impregnation. In a future section of this 

 report, I hope to be able to give the Board more extended information on 

 this point, as also with reference to the levels of the springs above mean 

 tide. Thus, by gauging and testing the streams at their sources, instead of 

 in their course and outfalls, we have the realisation of the principle laid 

 down by the Board; and this difference will account for the variance of my 

 results with those of Dr. Angus Smith. 



■riie annexed table of springs and rivulets gives their hardness, according 

 to Dr. Clarke's soap test, their daily discharge, and the number of houses 

 they are equivalent to at 75 gallons per house ; au addition of one-half the 

 average domestic consumption, as proved by an experiment instituted in the 

 district of Earl-street, London, on a block of 1200 houses of a fair average 

 class, the gaugings of the sewer gave 44i gallons, and of the butts and cis- 

 terns, 514 gallons per house. 



T.^HLE of Spriiiffs and Rivulets, showing their hardness, daili/ discharge, and 

 the number of houses each is equivalent to, at tlie rate of 75 gallons per 

 house. 



Names. 



Hindhead and Blackdotvn ^ ; — 

 Holy- water .. ,. 



Bramshot- 

 Down-lands 

 Headley-down 

 Barford-mills 

 Devil's-jumps 

 Punchbuivl 

 Cosford-hauge 

 Gray'a-wood 

 KotcUet 

 Five other springs 



Hascombe-hills a ; — 

 Siveetvvater-pond. . 

 liush-bridge 

 Chapel-copse 

 Hascombe .. 



Degrees 



of Hard. 



ness. 



Leilli-liiils4 _ 

 Totsfoid . . 

 Walton 

 Rooberj' 



Easthampstead Plain : — 

 Wishmoor,. 

 Broad-moor 

 Sandhnrst.. 

 Ambarroiv-hili 

 liarkham .. 

 Wokingham 

 BuU-brook. . 



Gallons dis- 

 charged per 

 day. 



Houses at 75 



gallons per 



house. 



Chobham-ridges : 

 Pirhright . . 

 Railway 

 Cow-moor .. 

 Coldingley . . 

 Folly 



Bagshot .. 

 Btistow-farm 



Farnham : — 

 Aqueduct .. 

 Minley 

 North'lieet . 

 Longbottom 

 Bramshill .. 

 Eversley . . 

 Castle. bottom 



North — 



Farnham-hill 



l,35l>,00(l 



I3,39!),714 



d40,O0IJ 



23U,7ai 



3,880,001) 

 .■JfiO.OUO 



aua,9ii.'> 



t)74,i)2S 

 84,240 

 22,568 



12/,5li2 



l,CS6,7!l.'i 

 .'i23,20U 

 224.6U7 

 229,1 Ki 



1,799,798 



sgo.a.ic 



I,43(!,40O 



810.000 

 460,000 



90,43.') 

 788,160 

 256,492 

 O/iO.OOO 



14,999 



45,848 

 Ui4,9M 

 6,426,000 

 31,809 

 4.-i,.'i72 

 74,779 

 270,000 



18,000 



178,622 



7,200 



3,197 



38,400 



15,000 



3,999 



8,989 



1,123 



434 



I,70U 



14,223 

 7,0.16 

 2,955 

 3,988 



23,977 

 11,8/9 

 19,53-.' 



10,800 

 6,134 

 1,285 



10,108 



3,419 



8,400 



199 



584 



1,798 



85,650 



424 



578 



997 



3,600 



1 Will be led away at one degree of hardness. 



f One and a-half degrees under the miU-wheel ; but will probably be led away at half 

 a degree of hardness. 



y Will be taken away at half a degree of hardness. 



■» Will be led away at one degree of hartlness. 



Giving altogether 39J millions of gallons, which might be brought to London at a 

 hardness certainly not exteediog one degree. I can answer for at least 10 millions more 

 under two degress of hardness. I must remark, that though these gaugings are only 

 offered as an approximation, 1 consider they will eventually iirovc to be rather under than 

 over-stated. 



I would remark that, where the springs flow into ponds dammed up for 

 the use of mills, I have taken the samples for tests from the springs them- 

 selves, as the evaporation alone of large surfaces of water generally adds two 

 and upwards degrees of hardness, and the waters are also exposed to dete- 

 rioration in colour, and, as I have found, in taste. For instance, at .Minley 

 Pond, itself situated between sand-hills, the springs do not show half a 

 degree of hardness, the pond one and a half; at" Sweetwater Pond the 

 springs have half a degree of hardness, the pond two degrees; at Bush- 

 bridge the springs have one degree uf hardness, Ihe pond nearly six. 



52 



