ISSO.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURxNAL. 



99 



how the elevations of the chnlk heneath the cl»y interposed diffi- 

 culties in obtaining a supply of water; clearly di'miinstratinjr that 

 it was the water in the sand-bed above tlie rlialk, and not the 

 water in the depths of the chalk, that was limited in (niantity; 

 and describing how, from the declivity of the chalk formation, tlie 

 fissures thereof under the alluvial dejjosits discharged the water 

 into the sand; and how the wells sunk only into tlie sand were 

 more or less subservient to each other. 



A discussion liere arose between Mr. Bhaitiiw.mte ami the 

 lecturer, the former endeavouring to jiruve tliat the increased 

 qiiantity of water at Covent-ganlen market liad been obtained by 

 improving and lowering the pumjjs of the well, and not altogether by 

 sinking the bore-pipe into tlie chalk. — Mr. T.ibberner said he "as 

 not contending for the mechanical superiority of one engineer 

 over another, but for the demonstration of the fact that for many 

 years Mr. Braithwaite had been endeavouring to obtain a sufficient 

 quantity of water for the market out of the sand-bed above the 

 chalk, and that he had not succeeded. Messrs. Easton and Amos 

 had subsequently bored 90 feet into the chalk, and thence ob- 

 tained a bountiful supply of water. This instance, and many 

 others which Mr. Tabber'ner adduced, shov.ed that Mr. Braith- 

 waite was wrong in his supposition that the principal body of 

 water was to be found in the sand and not in the chalk. 



Mr. Clarke, who had bored a great number of wells in and 

 around London, and who was then engaged in e.xtending the boring 

 of the Southampton deep well, here rose to support .Mr. Tabberner s 

 views. He had frequently bored considerable dejiths into the 

 chalk without obtaining water; but by continuing to bore deeper 

 he had always ultimately found an abundance of water. 



Mr. Tabberner then proceeded to describe the quality of the 

 chalk water, showing that reports as to its liard and chalybeate 

 qualities were not founded in truth. The carbonate of lime and 

 magnesia, which were the hardening constituents, did not amount 

 to 6 grains in the gallon, while the same constituents in the 

 Thames water amounted to from 10 to 12 grains in the gallon. He 

 further urged that the other properties contained in tlie chalk 

 water were essentially wholesome, and necessary to the natural 

 support of tlie human body. The rain as it fell on the exposed 

 surface of the chalk was pure water; but as it percolated through 

 the chalk fissures, it took up in its course, in a greater or less 

 degree, the carbonate of lime, magnesia, the alkaline, and other 

 constituents he had alluded to. He distinctly contradicted the 

 groundless supposition that the sea water found its way into the deep 

 wells of the chalk under London, and denounced the idea as a 

 theory perfectly fallacious and untenable. 



Mr. Braithwaite here again denied Mr. Tabberner's last posi- 

 tion to be correct, and gave Professor Brande as his authority. 

 He said, all deep wells, the water of whicli did not rise to the level 

 of Trinity low-water datum, were affected by the sea-water per- 

 colating into them, and instanced the deep wells at the Mint and 

 Trafalgar-square respectively, as producing water so affected. — Mr. 

 Tabberner took Mr. Braithwaite's own authority. Professor Brande; 

 and from a paper of the latter lately published, showed that the 

 solid contents found in the water of "the well at the Mint, were 38 

 grains in the gallon; and that the solid contents found in the water 

 at Trafalgar-square, were 68 grains in the gallon. He contended 

 that Mr. Braithwaite was again in the wrong; the salt and alka- 

 line properties of both wells differed in the same ratio, and there 

 were no two wells alike. He, Mr. Tabberner, therefore sulimitted, 

 whether, if both these wells— indeed all the deep wells— produced 

 sea water, they would not be identical in their constituents: tlie 

 fact of their not being so would not justify Professor Brande, Mr. 

 Braithwaite, or any one else, in the supposition that the water in 

 tlie deep wells, or what was commonly called Artesian wells, as 

 sunk into the chalk formation under London, were impregnated 

 with sea water. 



Mr. Clarke here said, that he had bored the well at the Mint, 

 and that Professor Brande had told him that the water raised from 

 it was very pure. 



Captain Moorsom asked Jlr. Tabberner, whether it was not true 

 that many of the London brew ers had been in great difficulties 

 with regard to their supply of water from the chalk; and if they 

 had not been compelled to deepen their wells.'' 



Mr. Tabberner said they had, as he had already admitted; and 

 it would be contrary to common-sense and the natural laws of 

 hydraulics, to suppose that the level of the water of the chalk did 

 not lower as the number of wells sunk into it increased. There w as 

 but an average of 21 inches of rain fell ujion the chalk surface; 

 and supposing only 10 inches of the whole quantity percolated 



through the fissures into the depths of the chalk, only that quan- 

 tity could be found in it; and supposing that first 100 wells were 

 sunk, then 200, tlien 500, and so on, it was very natural and a 

 necessary deduction, that the original level of the water would be 

 gradually lowered; but as the wells were deepened into the vale 

 of the chalk formation, the water would be found in proportion to 

 the deptlis in greater abundance, and the general level of the water 

 contained in the fissures would vary according to the quantity of 

 rain and snow falling on the exposed surface of the chalk; and in 

 proportion to the quantity of rain so falling, repletion would be 

 afforded to the wells — and' he had no doubt in his own mind, that 

 from 400 to 500 million gallons of water might be raised from the 

 depths of the chalk stratum per diem. He estimated the cost of 

 an Artesian plant, consisting of 100 wells and engine power, 1,200 

 miles of 7-inch main piping, and the contingencies pertaining to 

 an undertaking competent to supply from 30 to 50 million gallons 

 of water every 24- hours, at 1,700,000/. The annual cost of a con- 

 tinuous high and low service to every house, he estimated at about 

 70,000/., or about ifrf. per 1000 gallons. 



IMr. Tabberner concluded his lecture by a statistical exposition 

 of the saving that might be effected to the public, by taking the 

 water supply out of the hands of trading bodies, and hereafter 

 placing it under the control and management of a public elective 

 board,~as public property, subjected to the supervision of govern- 

 ment. He would first urge upon the government the necessity of 

 introducing a measure into Parliament, which should provide for 

 such a board, with powers to raise money upon the future rates, to 

 be equally levied according to the assessment upon every house 

 throughout the metropolis, the ground landlords being made liable 

 for the rate, which liability should enjoin compulsory powers to 

 extend the water su])ply to every house, and to make such supply 

 a part and parcel of the fee-simple; while every site applied to 

 future erections of any denomination whatever, should be charge- 

 able with the cost of extension of %vater-service mains and pipes to 

 such property as it was used for building purposes. He would 

 then raise sufficient means to purchase the jdants and interests of 

 the existing companies, which he would turn to sanitary purposes, 

 and provide an entire new continuous plant for domestic purposes, 

 the whole cost of which he computed at about 4,500,000/., which 

 he stated might be raised without asking government or the rate- 

 payers for one shilling, while the average rates might immediately 

 be' reduced very considerably. Thus would he restored to the 

 inhabitants that indefeasible 'public right to this first necessity to 

 man's subsistence, which was formerly enjoyed by the citizens of 

 London prior to the corporation transferring that right to commer- 

 cial speculators. Mr. Tabberner set forth his calculations in the 

 following form:— The present population was 2,336,000; and divid- 

 ing that number bv 7 (the mean number of inhabitants, according 

 to the Registrar-General's Report, to every house), the number of 

 houses comprising the metropolis, would be 333,000 houses, or say, 

 for the sake of round numbers, 330,000, to each of which he would 

 supply an average of 175 gallons of water, or 25 gallons to each 

 individual of a population of 2,336,000, every day, at an average 

 annual cost of 8,<(. per house, estimating the cost of water (in 

 accordance with the prime cost to the existing companies, and also 

 of the proposed new schemes), at Urf. per 1000 gallons. 



This average rate of 8s. upon 330,000 houses, would £ 



produce 133,000 



I'o pay 4 per cent, on 4,500,000/., he would require an 

 additional average rate of lis. 3d. on 330,000 houses, 



which would produce 180,000 



To raise a liquidating fund to pay off the 4,500,000/. 

 borrowed over a term of 30 years, he would require 

 a further average rate of 6*. 3d. on 330,000 houses, 

 producing 100,000 



Or a total average rate of 25s. 6d. per house, produc- 

 ing a gross annual revenue of i,413,000 



This average rate of 25s. 6rf. per house would be gradually 

 reduced as the progress of annual liquidation went on, till the 

 whole debt was discharged, and the whole water sujiply becon e 

 free to the inhabitants at the mere cost of conveyance, whic.'i 

 result, under good and economical management, would be accom- 

 plished in a much less term than 30 years. 



The average rate for every house supplied by the present 

 companies was, in the year 1833, 30.?. lO^rf., 5«. 4^rf. milre than tlie 

 total average required by Mr. Tabberner to accomplish all lie 

 proposes; and presuming that the average rate now charged by 

 the companies is not less than it was in 1833, it will appear that the 



