240 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[JUAY, 



of water standing above the bottom; there are two wells, one 110 ft. deep 

 and the other 120 ft., which are connected together by a tunnel driven from 

 within 4 or 5 ft. of the bottom of the deeper well to the bottom of the 

 other ; from this tunnel a verj- copious sujiply is ohtaiuc'l at all times ; after 

 10 hours' successive pumping the water is lowered 10 ft., and regains it after 

 the pumps have ceased working in three hours. 



The water is raised by the aid of an 8-norse engine, working two 8-inch 

 pumps, 22-inch stroke, and 20 strokes per minute, liftii-.g 160 gallons per 

 minute, or ll.'>,200 gallons in 12 hours. There is a well within 120 yards 

 of the above wells belonging to the mill, 90 ft. deep, which has never been 

 effected by the pumping at the above works. 



I'amsgate. — This town is entirely supplied by wells in the chalk, and 

 water-works ; principally, however, from tlie latter, which obtain their supply 

 ftom a well sunk in the chalk, the surface of which is 177 ft. above high 

 water mark ; the depth is 183 ft., of an oval shape, 9 and 6 ft. diameter ; 

 the lower 25 ft. is enlarged to 25 ft. diameter, from the sides of which there 

 are two tunnels, one 42 ft. long, and the other 25 ft., which supply an abun- 

 dance of water, issuing from fissures in the chalk ; there is generally 20 ft. 

 of water, which is reduced to 16 ft. after the engines have been working 12 

 hours. The water is raised by means of a 12-borse engine, working two 

 14-inch pumps in two lifts, 24-inch stroke, and 16 per minute, which lift 

 224 gallons per miuute, or 153,720 gallons per 12 hours. There is also a 

 smaller engine of 6-horse power, working two 9-inch pumps occasionally. 

 The large engines are worked three days per week. The water-works supply 

 about 700 houses, two or three breweries, malthouses, and shipping; a de- 

 ficiency has never been known. There is a well belonging to a cottage within 

 100 yards of the above well, and 160 ft. deep, which has never been affected 

 since the works have been erected, nor has there been a single complaint in 

 the town. 



The water is raised into an open reservoir near the engine-house, and con- 

 veyed by a 9-incb main the distance of IJ miles to the town. 



Cantebbhry. — This city is principally supplied from wells sunk in the 

 chalk. 



Gravesend. — This town is supplied by a well sunk in the chalk, and also 

 by water-works near Windmill Hill, where there is a well sunk entirely in 

 the chalk, 138 ft. deep ; at the bottom there is a tunnel from which the 

 springs issue ; the water is raised by the aid of an 8-horse engine, working 

 two 12-inch pumps, 24-inch stroke, and 10 strokes per minute, which is 

 195 gallons per minute, or 140,000 gallons per 12 hours. 



About four years ago an action was brought against the Water-works 

 Company by the proprietor of a well in the vicinity of the works, for a sup- 

 posed injury. Tlie proprietor alleged that his well was affected when the 

 engine was working, and shortened his sujiply. The case was referred to a 

 barrister, who examined several engineers and others, whose evidence was so 

 contradictory that he made a personal e.^amioation on tlie spot : after sealing 

 down the cover of the well, the engines were kept working, under his direc- 

 tions for a certain length of time ; and after the time was conchided, the well 

 "was again examined. Subsequently the barrister decided in favour of the 

 company. I have not yet been able to obtain the precise particulars of the 

 inquiry, hut the above statement shows that the barrister did not consider 

 that the well was affected. 



Nearly 40 years since a speculation was commenced, to make a tunnel 

 under the Thames at Gravesend. A shaft was dug, and a powerful steam 

 engine erected, a little to the westward of the gas-works, under the superin- 

 tendence of Mr. Uodd, the engineer. After an expenditure of several 

 thousand pounds, it was found impossible to get rid of the water. The 

 stratum was chalk. The water was perfectly fresh, although the river water 

 in this part of the Thames is brackish. 



St. Albans. — This town is supplied by wells sunk in the chalk, and by 

 water-works which obtain their supply from a well sunk in the chalk to the 

 depth of 1G3 ft. The water rises to the height of 19 ft., and is raised by the 

 aid of a steam engine of 8-horse power, working a 5-5-in-b double acting 

 pump, 24-inch stroke, and 20 strokes per raiunte, which lifts 82 gallons per 

 minute, or 59,040 gallons per 12 hours. After pumping that period, the 

 water is reduced to 9 ft. In the immediate neighhourliood of the viorks 

 there are several wells, one within 20 ft., none of which were ever affected 

 by the pumping of the above engine. 



The above extracts from reiiorts made by gentlemen who visited the various 

 places, must, I am persuaded, go far to satisfy the most sceptical that the 

 chalk formation is everywhere ahundanlly charged with water; they in fact 

 demonstrate, that many very important towns are at this moment actually 

 deriving their supply from that rock which Mr. Webster denies to be a water- 

 bearing stratum ; and whilst reflecting on this fact, it should not be forgotten 

 that, in all the instances just alluded to, no resources beyond small wells and 

 a few short drifts were required to afford supplies which should not be 

 regarded as inconsiderable, more especially when connected with a statement 

 that water cannot be obtained abundantly from the chalk formation. 



I cannot, however, content myself with extracts from reports made by 

 parties who may be supposed to be prejudiced in favour of the project with 

 which they are connected. I must, therefore, insert a few passages from 

 "Conybeare and Phillip's Geology," — a work, whether we regard it as de- 

 scriptive of the state of geological science at the period of its publication, or 

 as a record of an extraordinary mass of practical facts intimately connected 

 with the science, alike deserving admiration. 



In speaking of the chalk formation, tliey say — 



The ower beds H t x chalk formation and every fissure, are, with few 



exceptions, completely filled with water. All the rain and snow which fall 

 upon chalk percolate downwards to the base, where the water is stopped by 

 a sub-soil of blue clay, and that occasions it to accumulate in Wie chalk, 

 until it rises to such a height as doth enable it to flow over the surface of 

 the adjoining land." 



" Id this manner are formed the springs and rivulets which issue near the 

 foot of every chalk hill." 



These are the observations and conclusions acquiesced in by parties who 

 were influenced solely by the investigation of truth. They were not swayed 

 by any particular bias ; their opinion cannot be supposed to be affected by 

 one motive beyond those which science demands. 



Having, therefore, I trust, satisfactorily proved that the chalk abounds with 

 water, ii will naturally be expected that I should meet the question of 

 quantity; for upon this some of my anonymous assailants establish their 

 case, not, I must confess, without a show of probability, provided we admit 

 that what has not hitherto been done is impracticable. 



I grant, at once, that the quantity of water — viz., 8.000,000 gallons per 

 diem, which it is now proposed to raise from a shaft or shafts sunk in the 

 chalk, has no precise precedent ; but, surely, this admission is no argument 

 against the possibility ; on the contrary, I hold that the fair deduction from 

 the above record of facts is, that ttiis or a m^ich targrr mtpply may be 

 ol/taiiifd from the chalk, from prosecuting the sinking of shafts much deeper 

 than has hitherto been attempted, together with the extension of horizontal 

 driftways from the bottom of the shafts. 



On mentioning the horizontal driftways, it is perhaps unnecessary to reply 

 specifically to Mr. Webster's observations on this expedient for procuring an 

 increased supply ; for when he speaks of " groping" in the dark for water, 

 it is obvious that he is unacquainted both with mining and with the precise 

 nature of the construction of the chalk rock, and particularly in reference 

 to the character of the fissures which intersect its mass in every possible di- 

 rection — sometimes, it is true, more in one direction than another — easily, 

 however, determinable by observation. 



Mr. Webster playfully opens his remarks by observing that "Many are old 

 in years, yet young in geology." This assertion I will not attempt to dispute, 

 but state another, which I hope Mr. Webster will as readily concede — viz., 

 " Some are old in years, yet young in mining." When Mr. Webster has 

 spent as much of his time underground as I have done, and not till then, 

 will he understand the exact truth of this remark. I will not permit myself, 

 however, in this place to make any remark in disparagement of Mr. Webster, 

 as I am convinced any observation of a personal nature never, in a question 

 of this sort, can be substituted with propriety, for sound arguments or fair 

 deduction. 



With respect to the extent of supply, therefore, 1 would at once refer to 

 every mining district in this or any other country. Can we look at Cornwall 

 (when considering the matter in reference to the supply of water from chalk, 

 as a rock abounding with water,) without concluding at once that increasing 

 the depth of our shafts beyond those examples already quoted would be 

 attended by a prodigious augmentation in the flow of water to the well. The 

 extension of the under-ground workings of a mine, and the concomitant 

 increase in the supply of water, are equally calculated to bring to the mind 

 the overpowering conviction, that similar results would inevitably follow 

 the adoption of deeper shafts and a more extended system of drifts than 

 have hitherto been attempted in the chalk. To minds unhabituated to such 

 consideration, these general allusions to mines may not present the same 

 conviction; but to the experienced miner, I am persuaded the conclusions I 

 have drawn from the facts (exhibited by the wells suuk in the clalk near 

 Watford and elsewheie) will appear as necessary consequences. 



It was my wish, in this Report, to have cited some well-authenticated 

 particulars relative to the quantity of water raised from mines in different 

 parts of this country, believing that they would have borne out my views in 

 the strongest possible way; but on pursuing my inquiries upon this subject, 

 I found that I could only arrive at general results, for it unfortunately happens 

 that accurate records, in a shape calculated to be of value, are not kept in 

 the various mining districts. In Cornwall, however, this remark does not 

 apply so forcibly, for a precise record of the performances of all the pumping 

 engines employed in draining the mines is published in " Lean's Monthl) 

 Reports." 



From these Reports it is ascertained that upwards of thirty milUons of 

 gallons of water are daily raised from great depths to the surface, and from 

 the consolidated and united mines alone, the daily quantity exceeds 54 

 millions of gallons. 



There c;.n be no doubt that, were similar records kept of the quantity of 

 water raised to the surface in other mining districts of this country, that 

 results equally if not more striking would he exhibited, nor should we, in 

 the comparison, neglect to notice tlie fact that, unlike the chalk, the primary 

 strata of Cornwall in which the mines are suuk possess but limited channels 

 for the free communication of the water. 



These allusions to the mining districts may he deemed, perhaps, by some, 

 as altogether irrelevant and inapplicable to the point under consideration, 

 since the shafts are scattered over an extensive space of country. This is 

 certainly true when we speak of Cornwall ; but the objection is to a certain 

 degree obviated by specific allusion to the consolidated mines, and I can for- 

 tunately advert to another ease, respecting the quantity of water which may 

 be obtained from one or two shafts — an instance which, I think, must be 

 considered unequivocal. 



In the county of Durham two shafts within a few yards of one anothe . 



