Figs. 255-258.Reference.—P. Passy. G. Grenelle. B. Butte-aux-Cailles.R. Sugar Refinery.Larger image(208 kB)
Figs. 255-258.Reference.—P. Passy. G. Grenelle. B. Butte-aux-Cailles.R. Sugar Refinery.
Larger image(208 kB)
The operations were undertaken by Kind under a contract with the Municipality of Paris, by which he bound himself to complete the works within the space of twelve months from the date of their commencement, and to deliver the above quantity of water for the sum of 300,000 francs, 12,000l. On the 31st of May, 1857—after the workmen had been engaged nearly the time stipulated forthe completion of the work, and when the boring had been advanced to the depth of 1732 feet from the surface—the excavation suddenly collapsed in the upper strata, at about 100 feet from the ground, and filled up the bore. Kind would have been ruined had the engineers of the town held him to the strict letter of his contract; but it was decided to behave in a liberal manner, and to release him from it, the town retaining his services for the completion of the well, as also the right to use his patent machinery. The difficulties encountered in carrying the excavation through the clays of the upper strata were found to be so serious that, under the new arrangement, it required six years and nine months of continuous efforts to reach the water-bearingstratum, of which time the far larger portion was employed in traversing the clay beds. The upper part of this well was finally lined with solid masonry, to the depth of 150 feet from the surface; and beyond that depth tubing of wood and iron was introduced. This tubing was continued to the depth of 1804 feet from the surface, and had at the bottom a length of copper pipe pierced with holes to allow the water to enter. At this depth the compound tubing could not be made to descend any lower; but the engineers employed by the city of Paris wereconvinced that they could obtain the water by means of a preliminary boring; and therefore they proceeded to sink in the interior of the above tube of 3.2809 feet diameter, an inner tube 2 feet 4 inches diameter, formed of wrought-iron plates 2 inches thick, so as to enable them to traverse the clays encountered at this zone. At last, the water-bearing strata were met with on the 24th of September, 1861, at the depth of 1913 feet 10 inches from the ground-line; the yield of the wellbeing, at the first stroke of the tool that pierced the crust, 15,000 cubic mètres in 24 hours, or 3,349,200 gallons a day; it quickly rose to 25,000 cubic mètres, or 5,582,000 gallons a day; and as long as the column of water rose without any sensible diminution, it continued to deliver a uniform quantity of 17,000 mètres, or 3,795,000 gallons a day. The total costof this well was more than 40,000l., instead of 12,000l., at which Kind had originally estimated it.
Figs. 259, 260.Boring at Grenelle, Paris.
Figs. 259, 260.Boring at Grenelle, Paris.
Figs. 261, 262.Boring at Grenelle, Paris—continued.
Figs. 261, 262.Boring at Grenelle, Paris—continued.
Figs. 263, 264.Boring at Passy, Paris.
Figs. 263, 264.Boring at Passy, Paris.
Figs. 265, 266.Boring at Passy, Paris—continued.
Figs. 265, 266.Boring at Passy, Paris—continued.
Figs. 267, 268.Well at Ponders End.Larger image(217 kB)
Figs. 267, 268.Well at Ponders End.
Larger image(217 kB)
It may be questioned whether the engineers of the town were justified in passing the contract with Kind to finish the work within the time, and for the sum at which he undertook it; but they certainly treated him with kindness and consideration,in allowing him to conduct the work at the expense of the city of Paris, for so long a period after the expiration of his contract. It seems, however, that the French well-borers could not at the time have attempted to continue the well upon any other system than that introduced by Kind; that is to say, upon the supposition that it should be completed of the dimensions originally undertaken. Experience has shown that both steining and tubing were badly executed at the well of Passy. The masonry lining was introduced after Kind’s contract had expired, and when he had ceased to have the control of the works; the wrought-iron tubing at the lower part of the excavation being a subsequent idea. It has followed from this defective system of tubing—the wood necessarily yielding in the vertical joints—that the water in its upward passage escaped through the joints, and went to supply the basement beds of the Paris basin, which are as much resorted to as the London sand-beds for an Artesian supply; and, in fact, the level of the water has been raised in the neighbouring wells by the quantity let in from below, and the yield of the well itself has been proportionally diminished, until it has fallen to 450,000 gallons a day. That the increased yield of the neighbouring wells is to be accounted for by the escape of the water from the Artesian boring is additionally proved by the temperature of the water in them; it is found to be nearly 82° Fah., or nearly that observed in the water of Passy. This was an unfortunate complication of the bargain made between Kind and the Municipal Council; but it in no respect affects the choice of the boring machinery, which seems to have complied with all the conditions it was designed to meet. The descent of the tubes and their nature ought to have been the subject of special study by the engineers of the town, who should have known the nature of the strata to be traversed better than Kind could be supposed to do, and should have insisted upon the tubing being executed of cast or wrought-iron, so as effectually to resist the passage of the water. At any rate, this precaution ought to have been taken in the portions of the well carried through the basement beds of the Paris basin, or through the lower members of the chalk and the upper greensand.
Ponders End, Middlesex.—At the works of the London Jute Company. It will be seen from theFigs. 267, 268, that this well is bored all but the top 4 feet, which is 5 feet across and steined with 9-inch work. The uppermost tube is 12 inches in diameter, decreased to 9 inches, and then to 8 inches, and ending with a 6-inch bore, unlined, in the chalk.
The strata passed were;—
Alluvium, 6 feet;—Feet.In.Clay and Mud36Peat26Sand and Shingle(Gravel).70London Clay, 15 feet;—Blue Clay80Sandy Clay (basement bed?)70Reading Beds, 491⁄2feet;—Dead Sand100Mottled Clays220Sand and Metal (pyrites?)10Sandy Clay30Sand and Pebbles40Dead Sand16Dead Sand and Pebbles10Sand and Pebbles70Thanet Sand(?), 35 feet;—Green Sand270Dead Sand80To Chalk1126In Chalk2906Total4030
The water at this well overflows.
Freshwater, Isle of Wight.—Well,Figs. 269, 270, sunk at Golden Hill for H.M. Government. The diameter of the shaftis 4 feet 6 inches, brickwork 9 inches thick, there are 3 feet in cement at the top of the well, and 3 feet 9 inches at the bottom. There are four courses in cement every 5 feet, internal work four courses in cement every 10 feet. The bore-hole is lined throughout with pipes of 6 inches, 5 inches, and 4 inches diameter respectively.
Figs. 269, 270.Well at Freshwater, Isle of Wight.Larger image(296 kB)
Figs. 269, 270.Well at Freshwater, Isle of Wight.
Larger image(296 kB)
Winchfield, Hants.—Well,Figs. 271 to 273, at the brewery of Messrs. W. Cave and Son. The shaft above the steining is lined with iron cylinders into which the bore-pipe is carried up.
Figs. 271-273.Well at Winchfield, Hants.Larger image(137 kB)
Figs. 271-273.Well at Winchfield, Hants.
Larger image(137 kB)
The strata passed were;—
Feet.Made Earth, Soil, Gravel, Blue Clayand Dead Sand350Dark Sandy Clay3Black Pebbles2Coloured Clay5Stone (septaria?)2Coloured Clay22Coarse Shifting Sands7Total391
The following Table, compiled from the Government Memoirs and other reliable sources, furnishes in a condensed form the most important particulars relating to wells, and trial bore-holes comprised within the geographical area known as the London Basin.
The first column gives the name of the place where the well is situated, the second column that of the county, and the third column the precise locality. The following abbreviations have been employed: B. for Bedfordshire; Berks, Berkshire; Bucks, Buckinghamshire; E., Essex; H., Hampshire; Herts, Hertfordshire; K., Kent; M., Middlesex; S., Surrey.
O.D. stands for, above Ordnance Datum; T., above Trinity high-water mark.