1850. J 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



103 



processes^ and regard the branches nf dynamical sciences, where this takes 

 place, as purely experimental. By this we ffain an immense advan- 

 tage, — viz., that in all those points of them where the abstract 

 dynamical principles do afford distinct conclusions, we obtain veri- 

 fications for our inductions of the highest and finest possible kind. 

 When we work our way up inductively to one of these results, we 

 cannot help feeling the strongest assurance of the validity of the 

 induction. The necessity of this appeal to experiment, in everything 

 relating to the motions of fluids on the large scale, has long been felt." 



We have thought proper to enter thus fully on the actual state 

 of hydrodynaniical engineering in connection with its own parti- 

 cular branch — the drainage of towns, and the little reliance to be 

 placed, henceforth, in the experience and practice which has pro- 

 duced the defects in, and evils of, the present existing works; and 

 which it is the business of the Metropolitan Commissioners of 

 Sewers to remedy, because we find there is a leaning on the part of 

 the " practical men" Mr. Rendel alludes to, to continue pursuing 

 the old track. "For his (Mr. Rendel's) own part, he felt he could 

 go with the opinion as to avoiding drainage into the Thames, a« 

 Jar as it could be avoided, in reference to obvious and practical conclu- 

 sions.''^'' He did not go one jot further; therefore while he went to 

 the full e.xtent of desiring to purge the Thames from the sewage 

 of London, be must be certain that when the plan was carried out, 

 that result would be obtained. ^^ He believed, that the plan they 

 had to-day before them, would go a great way in furthering this 

 object; it would, at all events, be a step in the right direction." 

 And yet it is an imperfect plan on the old intermittent principle, 

 with a fall into that river, of whose purification we have heard so 

 much stated by the Commissioners. Though unsatisfactory, our 

 present knowledge and practice in matters of town drainage, we 

 would still add, with the writer in the Times, already quoted: — 

 " If the science and resources of the 19th century are incompe- 

 tent to effect the drainage of the metropolis, otherwise than by its 

 river, so it must be; but let us ascertain the necessity, before we put up 

 with its consequences." 



In conclusion, the plan proposed appears to us defective, — 



Because the sewage of the whole portion of the metropolis, lying 

 south of the Thames, is to be poured into the river, thereby pol- 

 luting it, at one of two highly-peopled districts; and 



Because this discharge taking place at low water, involves the 

 consequences attending the effects of an up-tide thereon; 



Because a provision being made for flushing the branch-drains, 

 implies the possibility of periodical cesspools; 



Because the provision for flushing the main sewer, implies the 

 intermittent instead of the constant system of draining; 



Because of the impropriety of "flushing" manure already suffi- 

 ciently diluted with an ample supply of water; 



Because in the event of the sewage of the district being required 

 for agricultural purposes, the main sewer from Battersea to Dept- 

 ford, and its continuation to Woolwich, becomes a waste expen- 

 diture; 



Because of the expense attending such a scheme. 



10" We readily accept the condition, and consent to ask for nothing impossible."— 

 Leading article of tlie " Times,'" IVIooday, January 28th. 



11" Wlien we advLxate the purtficaiion of the 'ihames, it is with the same * sine qua 

 non' as lliat alleged by Mr. Rendel, ' that the result,' namely, ' should be really ob- 

 tained.' "— '■ Times," January l'8tb. 



WELL WATER. 



Analysis of the Well Wafer at the Royal Mint, with some Remarks on the 

 Waters of the London Wells. By Professor Brande, f.r.s., v pes.. &c. 

 (Extracted from a paper read before the Chemical Society of London.) 



In corisequence of tlie defective supply of water at the Mint, Professor 

 Brande was consulted on tlie best mode of obtaining a necessary supply of 

 pure water for that establishment, ile was aulhoristd by the master of the 

 Mint to consult with Mr. 'Ihomas Clark, an experienced well-engineer, in 

 reference to the subject ; and accordingly desired him to examine into the 

 condition anil capabilities of all the v\eds, shafts, and tunnels, connected 

 witb the supplies of water throughout the building. This exauiinatiun was 

 carefully and effectually accomplished, and it appeared that the several wells 

 were in a very dilapidated, and some of them in a very dangerous state : that 

 few ot Ibeni were so situated or conditioned as to admit of being sufficiently 

 or safely deepened, so as to yield an adequate supply of water ; and that, as 

 respected the wells in the several engine-bouses, tliey were mere reservoirs 

 connected with the tunnel-sbaft from the tower, and therefore almost 

 exclusively supplied from the muddy source of the lower moat. 



Having personally convinced himself of the correctness of this report, and 

 having had Mr. Clark's statement corroborated by Mr. George Rennie, he 



represented the matter in detail to the master of the Mi ;<, and suggested 

 three plans for consideration, namely : — 



1. To derive the requisite supplies of water from the water companies. — 

 2. To repair the present wells, and to deepen such of them as would admit 

 of that operation. — 3. To sink an entirely new well. 



Professor Brande strongly urged the adoption of the latter alternative, 

 which after due consideration, was agreed to. He therefore obtained proper 

 plans and estimates from Mr. Clark, which after having been submitted to 

 the Board of Works, and liy their direction to Major Jebb, were ultimately 

 ordered to be carried into execution. 



It may be right to premise, that the total depth of this new well is about 

 426 feet; that the depth from the surface down to the chalk is about 221 

 feet, and the borings into the chalk about 202 feet ; the following being the 

 well-sinker's account of the strata gone through, namely : — 



Feet. 



DTade earth 11 



Gravel and sand (with water).. ,. .. .. ,, ..13 



Blue clay, with a le»v sandy veins (no water) ,. .. .. 98 



Coloured sand and pebbles (abundance ot water).. .. .. 14 



Dark sand, with veins of clay (little water).. .. .. .. 4 



Mottled clay (dry) .. .. ,. 6 



Loamy sand and dark clay (little water) ., .. ,, ., 5 



Blue clay, with shells .. .. .. ,. .. .. .. 6 



White rock ((juite dry).. .. .. .. .. ., .. 3 



Green sandy rock and pebbles (dry). . ■• .. ., .. 3 



Loamy gieen sand and black pebbles (little water) .. ., 5 



Green s.nd and pebbles (abundance of water) .. .. ..6 



Dark sand, with shells. . 40 



Flints 10 



Chalk 202 



426 

 The lining of the upper part of the well through the gravel and into the 

 blue clay, is composed of stout cast-iron cylinders, IJincli thick, and eight 

 feet clear diameter ; they are made in five feet lengths, with internal 

 flanges three inches wide, packed and jointed with strong bolts and nuts; 

 these prevent all access of the land springs from above, Tiie shaft is then 

 steined to the depth of 88 feet (that is, nearly through the blue clay,) in 

 9-inch cemented brickwork ; after which, cast-iron cylinders are resumed of 

 seven feet diameter, and these are continued down to the chalk ; but after 

 passing through the stratum of mottled clay, they include a series of cylinders 

 of six feet diameter, the space between the outer and inner cylinders being 

 filled with gravel-pebbles; a bore-pipe, 20 inches diameter, and 45 feet long, 

 is then driven to about ten feet into the chalk, and through Ibis the boring 

 is continued by an 18-inch auger, to the entire depth of the well. This well, 

 and all the works connected with it, were completed at Christmas, 1846; 

 and on the 1st of January, 1847, the whole of the works of the Mint, and 

 the dwelling houses, were supplied with the water, which is raised in a six- 

 inch main to a height of 50 feet above the surface, or 130 feet above the 

 average level of the water in the well, and is delivered at the rate of 240 

 gallons per minute, by means of three pumps of 9-inch diameter, and 8-inch 

 stroke, into a tank supported upon a building of brickwork. This tank is 

 100 feet long, 30 wide, and 5 deep ; it contains, therefore, 13,000 cubic 

 feet of water, or 93,750 imperial gallons. Two six-inch cast-iron mains, 

 furnished with proper slide-valves, descend from this tank, one passing on 

 either side of the Mint, so as conveniently to supply the whole of the 

 establishment, the daily consumption of the water frequently exceeding 

 40,000 gallons ; besides which a daily supply of 6,000 gallons is delivered, by 

 means of a main laid from the Mint, across Tower-hill to the Tower, for the 

 use of the inhabitants and the garrison, there being at present no serviceable 

 wells in that fortress, and the water derived from the adjacent river being 

 objectionable in point of cleanliness. The average height which the water 

 attains in the shaft of the Mint well is 80 feet from the sutface. After a 

 day's pumping it is lowered, upon an average, 20 feet, but there it remains 

 stationary, the flow of water from below maintaining the level, or in other 

 words, delivering at the rate of about 240 gallons per minute. Before this 

 well was completed, and before the boring into the chalk had been accom- 

 plished, the water derived from it contained 44 grains of dry saline matter 

 in the imperial gallon. At present, the machinery being complete, and the 

 well in full and daily use, the mean of several experiments in reference to 

 the solid matter contained in the imperial gallon of the water, amounts to 

 37'5 grains. The substances contained in each gallon of the water are as 

 follows : — 



Sulphuric acid .. .. .. .. ** .. 7"-44 



Chlorine .. .. .. .. .. .. 6-31 



Carbonic acid (after boiling) . . . . . . . . 5"H4 



Silica .. .. .. .. .. .. .. 0-58 



Sodium (combined with chlorine) . . .. .. .. 4*22 



Sjda (combiaed with sulphuric and carbonic acids).. .. 1(1 82 



Lime .. .. .. .. .. .. .. 1-96 



Magnesia .. .. .. .. .. .. 0*71 



Organic matter 1 



Phosphoric acid V .. .. .. .. .. Traces. 



Iron J 



The water evaporated to one-fifth of its hulk, and filtered, had lost almost 

 every trace of lime and of magnesia, so that it is probable that the greater 

 part of these sulistances were held in the state of carbonates, by excess of 

 carbonic acid. The carbonate of lime forms films during boiling, which 

 subside, and appear under the microscope in the form of very minute 

 acicular crystals. The crystalline deposit obtained by slowly evaporating the 

 water after the precipitated carbonate of lime has been separated by filtra- 



15* 



