Water Supply: the Present Practice of Sinking and Boring Wells / With Geological Considerations and Examples of Wells Executed

by Ernest Spon

Cretaceous Strata.

Bishop Stortford.—The waterworks and well are situate west of the town, near the farm buildings known as Marsh Barns. The shaft is 160 feet deep, the bore-hole 140 feet. The following is a section of the strata;—

	Feet.
Boulder Clay	17
London Clay, 54 feet;—
Brown Clay	14
Black Clay	2
Black Sandy Loam, with iron pyrites	12
Black Clay, with lignite	11
Dark Grey Sand, with large pieces of sandstone and shells	15
Reading Beds, 451⁄2 feet;—
Black Clay	2
Brown Clay	20
Light Brown Sand	01⁄2
Variegated Sand	18
Brown Clay	4
Flints and Pebbles	1
To Chalk	1161⁄2
Chalk	1831⁄2
Total	300

The water rises to within 140 feet of the surface of the ground. The yield is 10,000 gallons a minute; only 25 gallons a minute from the bore; the rest from the headings driven north and south respectively at a depth of 154 feet.

Braintree.—The well sunk for the Local Board is in a field near Pod’s Brook. The shaft is 8 feet in diameter, steined with 9-inch steining, and carried down 55 feet, the remainder of the well being bored. Strata;—

Drift, 14 feet;—	Feet.
Sandy Gravel	5
Drift Clay	9
London Clay, 136 feet;—
Clay, with sand, shells, and septaria, the bottom part more sandy	126
Dark Sand, with a few shells, yielding much water	10
Reading Beds, 45 feet;—
Mottled Plastic Clays, getting more sandy lower down, and with specks of chalk	44
Coarse Black Sandy Clay	1
Thanet Sand (?), 33 feet;—
Light-coloured Sands, firm and hard, getting darker and more friable lower down	20
Light-coloured Sands, firm, changing to coarse and dark	13
To Chalk	228
Chalk, with much water, rising to about 12 feet from the surface	17
Total	245

The level of the ground is 140 feet above the sea-level; water stands 29 feet deep; yield about 11,500 gallons an hour.

Brighton.—This town has always been supplied from wells sunk in the chalk. One well is sunk near the Lewes Road, and has a total length of 2400 feet of headings driven in a direction parallel with the sea, and at about the coast-level of low water. These headings intercept many fissures and materially add to the yield.

A second well was sunk in 1865, at Goldstone Bottom, and headings driven to the extent of about a quarter of a mile across the valley parallel to the sea.

Goldstone Bottom is a naturally formed basin in the chalk, the lowest side of which, nearest the sea, is more than 60 feet higher than the middle or bottom of the basin. The water is obtained as at Lewes Road, from fissures running generally at right-angles to the coast-line, but they are of much larger size and at far greater distances from each other; whereas at the Lewes Road well it is rare that 30 feet of headings were driven without finding a fissure, and the yield of the largest was not more than 100 to 150 gallons a minute. At Goldstone nearly 160 feet were traversed without any result, and then an enormous fissure was pierced which yielded at once nearly 1000 gallons a minute; and the same interval was found between this and the next fissure, which was of a capacity nearly as large. The total length of the headings at Goldstone Bottom is 13,000 feet. The yield from each well is about 3,000,000 gallons daily.

Chelmsford.—The well belonging to the Local Board of Health, situated at Moulsham, yields about 95,000 gallons of water a day. It is sunk for 200 feet; the rest bored. Water overflowed at first, but now that the well is in use and pumped from, the water only rises to 76 feet from the surface. The following strata were pierced;—

	Feet. In.
Black Soil (Mould)	3 0
Drift, 631⁄2 feet;—
Yellow Clay	2 6
Gravel	12 6
Quicksand	44 6
Sand, with stones	4 0
London Clay, 1861⁄2 feet;—
Clay	104 0
Clay, with sand	50 0
Dark Sand	12 6
Clay Slate (? septaria)	0 9
Clay and Shells	4 0
Clay Slate (? septaria)	0 3
Dark Sand and Clay	9 6
Sand and Shells	4 0
Pebbles	1 6
Woolwich Beds;—
Sand	7 0
Red Clay	12 0
Clay and Sand	64 0
Dark Thanet Sand	30 0
To Chalk	366 0
Chalk, 202 feet;—
Chalk	88 0
Rubble	1 0
Chalk	113 0
Total	568 0

Cheshunt, New River Company.—Situate at the engine-house between the two reservoirs. The well is 171 feet deep, and is steined partly with brickwork and partly with iron cylinders. For 12 feet in depth the well is 11 feet 6 inches in diameter, and steined with 14-inch brickwork; for a farther depth of 44 feet it is 9 feet diameter, and steined with 9-inch brickwork; of the 44 feet, 41 feet are lined with cast-iron cylinders, 8 feet diameter, which are also carried to a depth of 105 feet from the surface. There are fifteen cylinders of this size in use, and they are succeeded by others 6 feet 10 inches diameter, of which there are six in use; these are again succeeded by two cylinders 6 feet diameter. The whole of the cylinders are 6 feet in depth. The bottom of the last cylinder is 118 feet from the surface, at which point they rest upon a foundation of 9-inch brick steining 7 feet in depth. At the bottom of the 6-feet cylinders the well widens out in the form of a cone 12 feet 6 inches diameter at the floor, which is 26 feet below the bottom of the 6-feet cylinder. In the centre of the well a bore-hole, 3 inches diameter and 27 feet deep, was made, and the well is provided on the floor-level with headings.

Section of Strata.	Feet. In.
Surface Earth	1 6
Gravel	8 0
London Clay, 47 feet;—
Blue Clay	45 0
Yellow Clay	2 0
Reading Beds, 51 feet;—
White Sand	12 0
Dark Sand	39 0
To Chalk	107 6
Chalk	63 6
Total	171 0

Dorking, Surrey, obtains its water supply from a well sunk into the outcrop of the lower greensand, at the south side of the town. The shaft is 11 feet in diameter and 160 feet deep, steined with 9-inch work laid dry. The yield is not more than 30 gallons a minute, owing to the unfortunate position of the well, but might be considerably increased if suitable means were adopted.

Harrow Waterworks.—The well is situate 430 yards to the west of the church. The surface of the ground is 226 feet above the Ordnance datum. There is a shaft for 193¹⁄₂ feet; the rest is a bore. In a bed of dark red sand 144 feet down, the water was very foul. Strata;—

	Feet. In.
Light Blue Clay, with light-coloured stone	19 11
Brown Clay, with white stone	54 11
Dark Mottled Clay	15 0
Similar Clay, with dark and green sand	4 0
The same, very hard	3 0
The same, very hard, and dark sand	2 0
Lighter-coloured Hard Clay	5 0
The same, and dark sand	6 0
Large Pebbles	0 6
Clay and Sand	5 0
Light Blue Clay	0 4
Light-coloured Stone, with red and blue spots	1 3
Mottled Clays	7 11
Yellow, Light Blue, and Green Clay	1 0
Dark Green Clay, with black veins and spots	5 0
Blue Clay	1 6
Very Hard Brown, Yellow, and Blue Clay	4 0
Light Brown Running Sand, with water	2 6
Hard Mottled Clays	6 6
Light Brown Dead Sand	8 8
Black Peat, with dark pebbles	0 6
Brown and Green Gravel, with flints	3 2
Green Clay	0 4
To Chalk	158 6
Chalk, with beds of flint 4 to 15 inches in thickness, 15 to 24 inches apart; 3951⁄2 feet down, from surface, a bed of flint 6 feet thick	254 0
Total	412 6

Water rises to a height of 125 feet below the surface. The yield is about 190 gallons a minute.

Figs. 243-245.
Well at Highbury.

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Highbury, Middlesex.—Well at the residence of H. Rydon, Esq., New Park. [Figs. 243 to 245]. The shaft is 4 feet 6 inches diameter, and 136 feet deep, steined with 9-inch work set in cement. The bore was commenced with a 12-inch hole, but the character of the ground was such that the successive reductions in size, shown in the enlarged section of the lining tubes, [Fig. 245], had to be made. When in the chalk the bore was continued some 48 feet unlined. The strata passed were;—

Gravel	3	feet.
London Clay, 111 feet;—
Blue Clay	110	„
Claystone	1	„
Reading and Thanet Sand, 85 feet;—
Mottled Clay	25	„
Coloured Sand	60	„
To Chalk	199	„
Chalk	50	„
Total	249	„

Kentish Town.—This well was sunk under the supposition that as the outcrop of the subcretaceous formations was continuous around the margin of the cretaceous basin surrounding and underlying the London tertiaries, except at the eastern border, those subcretaceous formations would be found under London, just as they actually were at Paris. This proved to be the case until the gault was passed, when a series of sandstones and clays was encountered, occupying the place of the lower greensand, but evidently of older geological character, and having many of the features of the new red sandstone.

Figs. 246, 247.
Boring at Kentish Town, London.

The surface of the ground, [Fig. 246], is 174 feet above Thames high-water mark. There is a shaft for 539 feet; the remainder being bored. The following detailed account of the strata is due to Prestwich.

Figs. 248, 249.
Boring at Kentish Town, London—continued.

London Clay, 236 feet;—	Feet.	In.
Yellow Clay	30	6
Blue Clay, with septaria	205	6
Reading Beds, 611⁄2 feet:—
Red, Yellow, and Blue Mottled Clay	37	6
White Sand, with flint pebbles	0	6
Black Sand, passing into the bed below	2	0
Mottled Green and Red Clay	1	0
Clayey Sand	3	0
Dark Grey Sand, with layers of clay	9	6
Ash-coloured Quicksand	6	6
Flint Pebbles	1	6
Thanet Sand, 27 feet;—
Ash-coloured Sand	10	0
Clayey Sand	4	0
Dark Grey Clayey Sand	11	0
Angular Green-coated Flints	2	0
Chalk, with Flints (? Upper Chalk), 2441⁄2 feet;—
Chalk, with flints	119	6
Hard Chalk, without flints	8	0
Chalk, softer, with a few flints	31	6
Nodular Chalk, with three beds of tabular flints	13	6
Chalk, with layers of flint	32	6
Chalk, with a few flints and patches of sand	9	6
Very Light-grey Chalk, with a few flints	30	0
Chalk, without Flints (Lower Chalk), 341 feet;—
Light Grey Chalk, and a few thin beds of marl	133	0
Grey Chalk Marl, with compact and marly beds and occasional pyrites	161	0
Grey Marl	20	0
Harder Grey Marl, rather sandy and with occasional pyrites	27	0
Chalk Marl, 591⁄4 feet;—
Hard Rocky Marl (? Tottenhoe Stone)	0	6
Bluish Grey Marl, rather sandy, lower part more clayey	58	9
Upper Greensand;—
Dark Green Sand, mixed with grey clay	13	9
Gault, 1301⁄2 feet;—
Bluish Grey Micaceous Clay, slightly sandy	39	0
The same, with two layers of clayey greensand	6	7
Micaceous Blue Clay; at base a layer full of phosphatic nodules	84	11
Lower Greensand (?), 1881⁄2 feet;—
Red and Yellow Clayey Sand and Sandstone	1	0
Compact Red Clay, with patches of variegated sandstone	4	0
Dark Red Clay	4	7
Red Clay, Whitish Sand, and Mottled Sandstone	3	0
Hard Red Conglomerate, with pebbles from the size of a marble to that of a cannon-ball	2	0
Micaceous Red Clay, mottled in places	26	0
Layers of White Sandstone and Red Sand	3	8
Mottled Sandstone	0	4
Red Sand and Sandstone, with pebbles (a spring)	2	0
Layers of Red Sandstone and White Sand	4	0
Pebbly Red Sand and Sandstone	1	0
White and Red Sandstone	5	0
Fine Light Red Sand	2	9
Hard Sandstone	0	3
Very Fine Light Red Sand	4	0
Red Clay	2	0
Clayey Sand	1	3
Red Sandy Micaceous Clay, with sandstone	2	5
Compact Hard Greenish Sandstone	10	0
Very Micaceous Red Clay	1	0
Grey and Red Clayey Sand	1	1
Light-coloured Soft Sandstone	2	1
Red Sand and Sandstone	6	2
Greenish Sandstone	4	0
White and Grey Clayey Sand, with iron pyrites	2	0
Reddish Clayey Sand, with layers of sandstone	3	8
Micaceous Red Clay	18	4
Greenish Sandstone	0	5
Red Mottled Micaceous Clay, with patches of sand	34	6
Red Quartzose Micaceous Sandstone	2	0
Brownish-red Clayey Sand and Sandstone	4	0
Very Hard Micaceous Sandstone, with pebbles of white quartz	4	0
Light Red Clayey Sand	10	0
Red Micaceous Quartzose Sandstone	8	0
Light Red Clayey Sand, small fragments of chalk	2	0
Whitish and Greenish Hard Micaceous Sandstone	6	0
Total	1302	0

The engravings, Figs. [246] to [249], which are on the authority of G. R. Burnell, do not exactly agree with Prestwich’s section, but in the main they are both alike. The following summary may be found of service;—

	Feet.	In.
London Clay	236	0
Lower London Tertiaries	88	6
Chalk	644	9
Upper Greensand	13	9
Gault	130	6
Lower Greensand (?)	188	6

Fig. 250.
Well at Michelmersh.

Michelmersh, Hants.—[Fig. 250] shows a section of a well in this village, comprised within the writer’s practice. The shaft is 4 ft. 6 in. in diameter and 400 feet deep, steined both above and below the chalk with 9-inch work, the upper course having rings of cement at every 12 inches.

The strata pierced were;—

	Feet.	In.
Surface Soil	4	0
Dark Clay	27	0
Chalk	250	0
Band of Calcareous Sand	2	6
Upper Greensand	17	0
Total	300	6

The water rises some 19 feet in the shaft, and is abundant, although up to the present its quantity has not been tested.

Mile End, Middlesex.—Well at Charrington, Head, and Co.’s brewery. [Figs. 251 to 253]. The surface is 33¹⁄₂ feet above Trinity high-water mark.

In the upper part there are three iron cylinders built upon 9-inch brickwork, which is carried down into the mottled clay. A 9-inch iron cylinder, partially supported by rods from the surface, rises some 28 feet into the brick shaft into which it is built by means of rings. Another iron cylinder is carried down into the chalk, the space between the cylinders being filled in with concrete.

The strata passed were;—

	Feet.	In.
Made Earth	7	0
Valley Drift, 6 feet;—
Sand	3	0
Gravel	3	0
London Clay, 86 feet;—
Blue Clay	7	0
Hard Brown Clay, with claystones	68	0
Brown Sandy Clay	2	0
Hard Brown Sandy Clay, rotten at bottom	9	0
Woolwich and Reading Beds	63	0
Thanet Sand, 40 feet;—
Green Sand	2	0
Brownish-green Quicksand and Pebbles	2	0
Brown Sand	2	0
Grey and Brownish-green Sand	2	0
Green Sand and Pebbles	2	0
Brown Sand	2	0
Green Sand and Pebbles	15	0
Grey Sand and small Pebbles	2	0
Dark Grey and Green Sand	10	6
Green Sand and Green-coated Flints	0	6
To Chalk	202	0
Chalk Flints	0	6
Hard Chalk and Water	2	0
Total	204	6

The water-level is some 103 feet from surface, and the yield 60,000 to 70,000 gallons a day.

Figs. 251-253.
Well at Charrington’s, Mile End.

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Norwich.—Well at Coleman’s works. After a few feet of alluvium the borer passed through hard chalk with flints at distances of about 6 or 7 feet apart, for 700 feet, with the exception of 10 feet at the depth of 500 feet where the rock was soft and of a rusty colour, thence the flints were thicker, namely, about 4 feet apart to the depth of 1050 feet. After this 102 feet were pierced of chalk, free from flints, to the upper greensand, a stratum of about 6 feet, and then gault for 36 feet. The whole boring being full of water to within 16 feet of the surface.

Section of strata;—

	Feet.
Alluvium	12
Hard Chalk, with flints	483
Soft Chalk	10
Hard Chalk	190
Hard Chalk, flints closer	350
Chalk without flints	102
Upper Greensand	6
Gault	36
Total	1189

Paris.—The wells sunk in the Paris basin, of which [Fig. 254] is a section, are very numerous, and many of them of great depth. [Fig. 255] is a plan indicating the position of the principal wells, and [Figs. 256 to 258] sections giving each a summary of the nature and thickness of the formations passed through.

Fig. 254.
Geological Section from Niort to Verdun, through the Paris Basin.
Horizontal scale, 90 miles the inch.
Vertical scale, 1500 feet the inch.

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For boring these wells special tools had to be used, which have already been described at length in Chap. VI.

A large Artesian well was, in 1867, being constructed by Dru at Butte-aux-Cailles, [Fig. 255], for the supply of the city of Paris, which is intended to be carried down through the greensand to a depth of 2600 or 2900 feet to reach the Portland limestone. The boring in 1867 was 490 feet deep, and its diameter 47 inches.

During the previous 2¹⁄₂ years, M. Dru was engaged in sinking a similar well of 19 inches diameter for supplying the Sugar Refinery of M. Say, in Paris, [Fig. 255]; 1570 feet deep of this well had been bored in 1867, see [Fig. 258].

The well at Grenelle was sunk by Mulot in 1832, and after more than eight years’ incessant labour, water rose on the 26th of February, 1842, from the total depth of 1806 feet 9 inches. The diameter of the bore-hole is 8 inches, ending, as is seen in the detail sections, Figs. [259] to [262], in the lower greensand.

The well of Passy was intended to be executed in the Paris basin which it was to traverse with a diameter, hitherto unattempted, of 1 mètre (3·2809 feet); that of the Grenelle well being only 20 centimètres (8 inches). It was calculated that it would reach the water-bearing stratum at nearly the same depth as the latter, and would yield 8000 mètres or 10,000 cubic mètres in twenty-four hours, or about 1,786,240 gallons to 2,232,800 gallons a day.

Figs. [263] to [266] show a detail section of the strata passed.

Figs. 255-258.
Reference.—P. Passy. G. Grenelle. B. Butte-aux-Cailles.
R. Sugar Refinery.

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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 for the 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-bearing stratum, 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 were convinced 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 well being, 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 cost of 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. 261, 262.
Boring at Grenelle, Paris—continued.

Figs. 263, 264.
Boring at Passy, Paris.

Figs. 265, 266.
Boring at Passy, Paris—continued.

Figs. 267, 268.
Well at Ponders End.

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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 the [Figs. 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 Mud	3	6
Peat	2	6
Sand and Shingle (Gravel).	7	0
London Clay, 15 feet;—
Blue Clay	8	0
Sandy Clay (basement bed?)	7	0
Reading Beds, 491⁄2 feet;—
Dead Sand	10	0
Mottled Clays	22	0
Sand and Metal (pyrites?)	1	0
Sandy Clay	3	0
Sand and Pebbles	4	0
Dead Sand	1	6
Dead Sand and Pebbles	1	0
Sand and Pebbles	7	0
Thanet Sand (?), 35 feet;—
Green Sand	27	0
Dead Sand	8	0
To Chalk	112	6
In Chalk	290	6
Total	403	0

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 shaft is 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.

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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.

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The strata passed were;—

	Feet.
Made Earth, Soil, Gravel, Blue Clay and Dead Sand	350
Dark Sandy Clay	3
Black Pebbles	2
Coloured Clay	5
Stone (septaria?)	2
Coloured Clay	22
Coarse Shifting Sands	7
Total	391

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.

PARTICULARS OF WELLS.
Name of Place.	County.	Locality.	Depth.
			of Shaft.	of Bore.	in Tertiary Strata.	in Chalk.	to Water from Surface.
			feet.	feet.	feet.	feet.	feet
			Remarks.
Abridge	E.	Brewery	100	190	290	—	30
			London Clay, 280 feet.
Acton	M.	Mr Engleheart’s	—	—	284	119	12
Ditto	„	Mr. Wood’s	—	—	315	135	40
Ditto, East	„	Mr. Davis’s	—	—	267	68
Albany Street	„	London	—	—	182	125	—
			100 feet O.D.
Aldershot Place	H.	— —	—	—	194	—	—
			260 feet O.D.
Ditto	„	— —	—	—	148	691⁄2	—
			245 feet O.D.
Amwell End	Herts.	New River Company	72	3473⁄4	36	3833⁄4	—
			Yield about 2,500,000 gallons a day.
Arlesey	B.	Asylum	100	365	7	120	—
			233 feet O.D.; water rises into shaft; yield 2640 gallons an hour.
Ash	S.	S.W. Railway Station	—	600	370	230	—
			290 feet O.D.
Bank of England	M.	London	137	1971⁄2	2341⁄2	100	88
			About 27 feet T.; yield, 35 gallons a minute.
Bagshot	S.	Orphan Asylum	123	523	646	—	—
			Last 192 feet London Clay.
Balham Hill	„	Near Clapham Common	—	—	347	—	—
			Last 40 feet Thanet sands.
Barking	E.	Byfron’s	140	—	140	—	30
			Bottom in hard pebbles.
Barnet, East	Herts.	Lion’s Down	122	270	162	230	130
			Shaft half steined, half iron cylinders.
Ditto, New	„	Near Railway Station	137	302	159	280	130
Battersea	S.	Jones’s Works	249	—	249
Ditto	„	Beaufoy’s Works	240	—	240	—	—
			Yield said to equal 15,000 gallons a day.
Bearwood	Berks.	Mr. Walters’s	—	—	350	15
Beaumont Green	Herts.	Near Cheshunt	1831⁄2	—	1261⁄2	57
Belleisle	M.	Pashes and Co.’s	—	—	185	118	118
Berkeley Square	„	London	160	156	224	92	80
Bermondsey	S.	Crimscott Street	—	—	120	—	—
			9 feet O.D.; yield plentiful.
Ditto	„	Donkin’s Works	—	232	911⁄2	1401⁄2	16
			Yield 30 gallons a minute.
Berry Green	Herts.	Hadham	40	20	60	—	8
Bexley	K.	Brickfield	65	110	1291⁄4	453⁄4	60
Bishop Stortford	Herts.	Waterworks	160	140	1161⁄2	1831⁄2	140
			Supply 10,000 gallons a minute.
Ditto	„	Hockerill	85	125	90	120	78
			Good supply.
Ditto	„	New Road	77	—	56	21
Blackfriars	M.	Apothecaries’ Hall	—	—	218	76
Blackheath	K.	Near Enfield Terrace	—	—	109	30
Boston Heath	„	Near Woolwich	—	—	130	70
Bow	M.	Starch Works	176	148	174	150
Boxley Wood	K.	Near Maidstone	3861⁄2	2131⁄2	3	600	—
			382 feet T.; last 781⁄2 feet in chalk, marl, and gault.
Braintree	E.	Near Pod’s Brook	55	190	228	7	216
			Yield, 11,500 gallons an hour.
Brentford	M.	Brewery	30	338	315	53	5
Bromley	K.	Gas Works	50	120	150	20	—
			Supply abundant.
Ditto	„	Widmore Kiln	52	98	140	10
Ditto	„	Ditto	55	85	120	10	61
Ditto	„	Tylney Road	77	85	137	25
Ditto	„	Waterworks	—	—	70	180	—
			Yield, 500 to 600 gallons a minute.
Broxbourne	Herts.	— —	84	—	84	6
			Water overflowed.
Bushey	„	Near Watford	142	24	145	21
Camberwell	S.	The Grove	—	—	208	3001⁄2	90
Camden Station	M.	L. and N.W. Railway	180	220	234	166	150
			100 foot O.D.
Camden Town	M.	Pickford’s	—	—	215	82	120
			Good supply.
Ditto	„	Whitaker’s Brewery	235	75	210	90	190
Canterbury	K.	Orphan Asylum	—	—	145	—	120
Caterham	S.	Waterworks	—	—	89	349	—
			709 feet T.; through chalk, and 39 feet into upper greensand.
Chelmsford	E.	Moulsham	200	368	366	202	76
			Water overflowed at first.
Cheshunt	Herts.	New River Company	144	27	1071⁄2	631⁄2	120
			Yield, 702,000 gallons a day.
Ditto	„	Theobald’s Park	71	1311⁄2	1211⁄2	81	65
Chiswell Street	M.	Whitbread’s Brewery	183	150	183	150	132
Chiswick	„	Griffin Brewery	204	200	297	107	—
			Yield, 14 gallons a minute.
Ditto	„	Lamb Brewery	203	194	293	104
Ditto	„	Ditto	8	339	297	50
Clewer Green	Berks.	Capt. Winterbottom’s	42	294	270	66
Ditto	„	Wycombe Cottage	20	246	169	97
Colnbrook	M.	Paper Mills	—	—	207	175	—
			Water found at 203 feet down.
Colney Hatch	„	Asylum	137	193	189	141
Covent Garden	„	Market	140	218	260	98	120
			70 feet O.D.
Cricklewood	„	Near Hampstead	225	85	291	19	110
			157 feet T.
Croydon	S.	Well for Local Board	77	—	11	62	—
			Yield 1,500,000 gallons a day.
Ditto	„	New Well	—	—	15	137	111⁄2
Dartford Creek	K.	Paper Mills	34	49	33	50	—
			Supply good.
Ditto	„	Ditto	10	2401⁄2	30	2201⁄2	2
Denham	Bucks.	Tile House	110	85	67	128	85
Deptford	K.	Waterworks	27	—	14	13	—
			20 feet O.D.
Dulwich	S.	Champion Hill	—	—	210	298
East Ham Level	E.	Beckton Gas Works	25	175	117	83	2
Edgware	M.	Mr. Day’s	—	—	290	45	40
Edgware Road	„	The Hyde	—	—	101	37
Edlesborough	Bucks.	Well, near Mill	—	301	—	—	70
			6-inch bore; through 50 feet of chalk marl to lower greensand.
Eltham	K.	Dr. King’s	46	—	46	—	17
Ditto	„	The Moat	110	—	100	10
Ditto	„	Mr. Tuck’s	44	123	1221⁄2	441⁄2	25
Ditto	„	Well Hall	—	107	104	3
Ditto Park	„	— —	—	—	122	94	170
Enfield Lock	E.	Small Arms Factory	45	2391⁄2	1521⁄2	132	4
Epping	„	Waterworks	275	129	400	4	260
			Slow spring.
Erith	K.	Mineral Oil Company	166	—	146	20
Farnham	S.	Near Hale Farm	176	—	80	96
Fleet Street	M.	London, Shoe Lane	100	225	100	225
Fulmer	Bucks.	J. Kay’s	85	—	473⁄4	371⁄4	—
			Through gravel and Reading beds.
Golden Lane	M.	Baths and Washhouses	158	—	1511⁄2	61⁄2	—
			65 feet O.D.
Gravesend	K.	Church Street	10	234	120	124	8
			Supply good and abundant.
Greenwich	„	Brewery	22	158	80	100	11
Ditto	„	East Street	189	—	159	30
Ditto	„	Hospital Brewery	155	150	1241⁄2	1801⁄2	19
			7 feet T.; supply 120 gallons a minute.
Hackney Road	M.	Wiltshire Brewery	96	3153⁄4	1523⁄4	259	80
Haggerstone	„	Imperial Gas Works	1181⁄2	302	1641⁄2	256
Hainault Forest	E.	— —	165	—	110	55
Halstead	„	The White Hart	—	—	170	30
Hammersmith	M.	Average of four wells	—	—	245	68	—
			Yield, 16 gallons a minute.
Hampstead	„	Lower Heath	320	130	378	72	—
			Now not used.
Hampstead Road	„	Eagle Brewery	138	94	146	86	147
Ditto	„	Reservoir	244	—	152	92	106
			77 feet T.
Hanwell	„	Asylum	230	90	290	30	—
			Water to surface.
Harrow	„	Waterworks	1931⁄2	219	1581⁄2	254	125
			226 feet O.D.
Haverstock Hill	„	Orphan School	230	160	312	78	196
			176 feet O.D.
Hayes	„	Dawley Court	19	300	231	88	27
Hendon	„	Mr. Booth’s	—	—	244	132	76
Highbury	„	Brewery	104	210	180	134	95
			Yield, 1000 gallons an hour.
Ditto	„	New Park	136	113	199	50
Hoddesdon	Herts.	New River Company	52	234	241⁄2	2611⁄2	2
Holloway	M.	— —	140	200	240	100
Ditto	„	City Prison	—	—	217	102
Ditto	„	Hanley Road	—	—	67	13
Ditto	„	Redcap Lane	—	—	210	90
Ditto	„	Islington Workhouse	234	306	299	250
Hornsey	„	Near Church	—	—	202	48
Ditto	„	The Priory	—	—	225	—	—
Horselydown	S.	Anchor Brewery	100	162	158	104	50
Hoxton	M.	— —	152	10	151	11
Hyde Park Corner	„	St. George’s Hospital	200	1371⁄4	3191⁄4	18	100
			50 foot O.D.; yield, 3300 gallons an hour.
Ickenham	„	Public Well	64	80	64	80
Isle of Dogs	„	Oil Mills	27	337	1241⁄2	2391⁄2	10
Isle of Grain	K.	Fort	180	140	320	—	20
			21 feet O.D.
Isleworth	M.	Sion House	—	—	420	115	—
			Water overflowed at the rate of 5 gallons a minute.
Ditto	„	Mr. Wilmot’s	—	327	327	—	—
			Water rose above surface.
Islington Green	„	Webb’s Mineral Water Works	—	320	176	144	200
Kensington	„	Brewery	—	—	197	—	—
			16 feet T.
Ditto	„	Britannia Brewery	100	170	270	—	88
Ditto	„	Horticultural Society	200	201	317	84	100
			60 feet O.D.
Ditto	„	Workhouse	—	—	270	100
Ditto Gardens	„	Serpentine	263	58	2631⁄4	573⁄4	105
			60 feet O.D.; yield, 250 gallons a minute.
Kentish Town	„	Waterworks	539	763	3241⁄2	6443⁄4	—
			Through London clay, 236 feet; London tertiaries, 881⁄2 feet; chalk, 6443⁄4 feet; upper greensand, 133⁄4 feet; gault, 1301⁄2 feet; and into lower greensand (?), 1881⁄2 feet.
Kilburn	„	Brewery	250	30	235	45	150
Kingsbury	„	Brent Reservoir	101	139	132	108
Kingston-on-Thames	S.	Brook Street	90	380	371	99	—
			25 feet O.D.; yield, about 44,000 gallons a day.
Knightsbridge	M.	— —	240	—	240	—	50
Lambeth	S.	Beaufoy’s Vinegar Works	100	275	201	174	—
			Yield, 92 gallons a minute.
Ditto	„	South Lambeth Road	25	166	187	4
Ditto	„	Bethlehem Hospital	30	161	191	20	15
Ditto	„	Lion Brewery, Belvedere Road	—	—	245	173	40
Ditto	„	Duke Street, Street, Clowes & Sons’	26	184	210
Lea Bridge	M.	Waterworks	118	—	100	18
Leicester Square	„	Alhambra	150	195	244	101
Limehouse	„	Johnson’s, Commercial Road	90	110	190	10
Ditto	„	Brewery, Fore Street	—	—	1391⁄2
Liquorpond Street	„	Reid’s Brewery	2221⁄2	40	136	1261⁄2	121
			70 feet O.D.; yield, 277,200 gallons in 24 hours.
Long Acre	„	Combe & Co.’s Brewery	263	228	223	268	—
			70 feet O.D.; yield, 90 gallons a minute
Loughton	E.	— —	—	535	324	211	90
			No water from chalk.
Lower Morden	S.	On the Green	20	365	340	45	—
			Water to surface.
Luton	B.	Waterworks	50	272	—	322
Maldon	E.	Waterworks	234	—	234	—	—
			Entirely through London clay.
Margate	K.	Cobb’s Brewery	31	243	—	374
Marylebone Road	M.	London; a Brewery	186	101	232	55	156
Mile End	„	Mann’s Brewery	195	—	185	10
Ditto	„	Charrington’s Brewery	204	—	202	2	103
			331⁄2 feet T.; yield, 60,000 to 70,000 gallons a day.
Ditto Road	„	City of London Union	—	—	175	10
Millbank	„	Distillery	115	190	205	100	70
			Level of T.
Ditto	„	Westminster Brewery	—	—	225	70	—
			51⁄2 feet T.
Mitcham	S.	Nightingale’s Factory	—	211	189	22
Monkham Park	E.	Near Waltham Abbey	225	125	304	76	50
Mortlake	S.	Mortlake Brewery	30	288	287	31	50
			Yield, 14,000 gallons a day.
Ditto	„	Mr. Randell’s	—	365	315	50
New Cross	K.	Naval School	50	130	125	55	60
Northolt	M.	Near Harrow	12	228	180	60	4
Notting Dale	„	Near Notting Hill	—	—	244	12
Notting Hill	„	Mr. Knight’s	—	—	230	200
Old Kent Road	S.	Welsh Ale Brewery	—	—	30	170	—
			10 feet O.D.
Old Windsor	Berks.	Pelham Place	—	—	222	9
Ditto	„	The Union	60	180	240	47
Orange Street	M.	Back of National Gallery	174	126	250	50	115
			42 feet T.
Oxford Street	„	Star Brewery	166	170	158	178
Peckham	S.	Marlborough House	—	—	100	123
Penge	„	Palace Grounds	250	310	358	202	90
Pentonville	M.	Brewery, Caledonian Road	2191⁄2	—	2191⁄2	45	180
			To chalk.
Ditto	„	Prison	170	2001⁄2	2191⁄2	151
Pimlico	„	Cubitt’s Works	188	—	188	—	—
			2 feet T.
Ditto	„	Brewer Street	30	368	271	127
Ditto	„	Simpson’s Factory	—	—	231	100	36
			1 foot T.
Pinner	„	Hatch End	140	—	60	80
Plaistow	E.	Odam’s Manure Works	—	—	1701⁄2	128
Ponders End	M.	London Jute Company	4	399	1121⁄2	2901⁄2	—
			Water overflows.
Ditto	„	Crape Works	20	42	62
Ditto	„	Local Board (Speller)	—	—	106	961⁄2
Ditto	„	Waterworks	23	181	97	107	—
			43 feet T.
Pudsey Hall	E.	Near Canewdon	297	—	297	—	—
			Water abundant and good.
Ratcliffe	M.	Queen’s Head Brewery	—	—	160	200
Ditto	„	Marine Brewery	16	236	150	102
Ditto	„	Ravenhill’s	—	137
Regent’s Park	„	Colosseum	150	100	171	79
Ditto	„	Mr. Day’s	—	—	184	216	80
Ditto	„	Zoological Gardens	183	91	224	50	120
			Yield, 90,000 gallons a day.
Richmond	S.	Old Waterworks	—	—	276	103
Ditto	„	Star and Garter	—	—	416	76
Romford	E.	Ind, Coope, & Co.	155	—	145	10
Rotherhithe	S.	Brandram’s Works	30	222	107	145	27
			Yield, 100,000 gallons in 12 hours.
Ditto	„	Tunnel Flour Mills	—	—	125	135	—
			15 feet O.D.; yield, 80 gallons a minute.
Ruislip	M.	Near “The George”	15	903⁄4	753⁄4	30	—
			Water to surface.
Saffron Walden	E.	— —	—	—	—	1000
Sandhurst	Berks.	Well at College	—	603	—	—	—
			Trial boring; chalk reached.
Sandwich	K.	The Bank	70	—	62	8	20
Sheerness	„	Waterworks	300	84	384	—	—
			51⁄2 feet O.D.; yield, 10,000 gallons an hour.
Ditto	„	Dockyard	330	125	455	—	53
			Yield, 675 gallons an hour.
Shoreditch	M.	Truman’s Brewery	300	230	199	331	120
			Yield, 71⁄2 gallons a minute.
Shorne Meade Fort	K.	Near Gravesend	112	—	771⁄2	341⁄2
Shortlands	„	Near Bromley	59	150	109	100	61
			Yield, 1000 gallons an hour.
Slough	Bucks.	Eton Union	28	103	107	24
Ditto	„	Royal Nursery	—	—	94	171⁄2
Ditto	„	Upton Park	—	—	1021⁄4	1701⁄4
Ditto	„	Waterworks	117	—	90	27	7
			Heading into chalk.
Smithfield	M.	Booth’s Distillery	—	—	230	70	70
Southend	E.	Waterworks	417	—	417	—	100
			Old well.
Southwark	S.	Barclay’s Brewery	115	288	212	211	—
			Level of T.; yield, 300 gallons a minute.
Ditto	„	Guy’s Hospital	132	173	196	109	84
			2 feet T.; yield, 33 gallons a minute.
Staines	M.	Ashby’s Brewery	—	—	369	154	—
			Water to surface.
Stifford	E.	S.E. of Church	63	—	33	30
Stockwell Green	S.	Waltham’s Brewery	100	210	210	100	46
			Yield, 33 gallons a minute.
Ditto	„	Hammerton’s Brewery	25	186	211	154	—
			Yield, 46 gallons a minute.
Stratford	E.	Great Eastern Works	56	344	106	294
Ditto	„	Savill Bros.’ Brewery	1121⁄2	—	1091⁄2	3
Ditto	„	Langthorn Chemical Works	60	395	132	323	—
			Supply abundant.
Streatham	S.	The Common	100	185	285
Sudbury	M.	London and North-Western Rail. Station	200	—	120	80
Tottenham	„	Warne’s Works	—	—	147	104
Ditto	„	Long Water	—	—	1491⁄2	1011⁄2
Ditto	„	Tottenham Hall	—	253	153	100
Tottenham Court Road	„	Meux’s Brewery	188	622	156	654	—
			85 feet O.D.; yield, 121⁄2 gallons a minute.
Tower Hill	„	Royal Mint	1951⁄2	202	1951⁄2	202	80
Trafalgar Square	„	London	168	228	248	148	—
			Yield, 450 gallons a minute.
Upchurch	K.	Burntwick Island	—	236	236
Ditto	„	Milford Hope Marshes	—	304	210	94	—
			Good supply at bottom.
Upper Thames Street	M.	City of London Brewery	90	415	210	295	10
Uxbridge	„	The Dolphin	121	—	811⁄2	391⁄2	3
Ditto	„	Near Market Place	—	—	104	28	151⁄2
Ditto	„	Page’s Lane	98	—	98
Ditto	„	Town Well	—	—	109	30	19
Ditto	„	Near “King’s Arms”	24	84	108	—	19
			To chalk.
Ditto	„	New Year’s Green Farm	63	—	63	—	51
Ditto	„	Hurdle Yard	78	391⁄2	78	391⁄2
Ditto	„	Near Meeting House	411⁄2	1091⁄2	115	36	39
Ditto	„	The Union	51	162	175	38	29
Vauxhall	S.	Burnett’s Distillery	140	186	224	102	55
			Yield, 80 gallons a minute.
Waltham Abbey	E.	Brewery	164	—	160	4	—
			Water supply from bed of sand.
Walthamstow Marsh	„	East London Waterworks	—	—	152	140	—
			15 feet T.
Wandworth	S.	Young & Bainbridge’s	170	164	274	60	45
			Yield, 10 gallons a minute.
Ditto	„	Prison	—	—	357	1261⁄2	80
			Yield, 27 gallons a minute.
Ditto	„	County Asylum	—	—	331	6	30
Westbourne Grove	M.	Hippodrome	240	67	300	7
West Drayton	„	Victoria Oil Mills	12	274	186	100	—
			Water overflowed.
Ditto	„	Vitriol Works	—	—	1331⁄2	451⁄2
Ditto	„	Drayton Mills	3	146	149	—	—
			To chalk.
West Ham	E.	Mr. Tucker’s	—	—	132	306
Ditto	„	Union	—	—	110	55
West India Dock	M.	South of Export Dock	—	—	120	240
Westminster	„	Artillery Brewery	—	—	230
Ditto	„	Chartered Gas Works	—	—	225
Ditto	„	Vickers’ Distillery	116	184	249	51	70
			Yield, 94 gallons a minute.
Ditto	„	Swallow Street	—	—	210	—	60
Whitechapel	„	Furze’s Brewery	130	218	248	100
Ditto	„	Smith’s Distillery	106	264	210	160	36
			36 feet T.
Ditto	„	Smith, Druce, & Co.’s	1411⁄2	—	1411⁄2	—	85
			39 feet T.
Willesden	„	Mr. Kilsby’s	—	—	273	97	30
Wimbledon	S.	Convalescent Hospital	200	367	537	30	50
Ditto, New	„	Opposite “White Hart”	—	—	193	75
Windsor	Berks	Clower Lodge	40	175	175	40
Ditto	„	Royal Brewery	72	—	72	—	—
			Through clay and running sand to chalk.
Ditto	„	Jennings’ Brewery	—	—	30	500	12
Winkfield Plain	„	Captain Forbes’	—	—	304	126	70
Witham	E.	— —	—	—	306	—	5
Woodley Lodge	Berks.	3 miles east of Reading	95	35	130
Woolwich	K.	Well of Arsenal	—	—	541⁄2	3111⁄2	37
Ditto	„	Paper Factory	—	550	51⁄2	5441⁄2	—
			Yield, 650 gallons a minute.
Ditto	„	Dockyard	—	608	20	588	70
			Yield good.
Wormley	Herts.	Nunsbury	26	761⁄2	801⁄2	22	—
			Water overflows.
Ditto	„	West End	85	1501⁄2	72	631⁄2	62
Wormwood Scrubbs	M.	— —	—	—	250	116	5

---

[CHAPTER VIII.]
TABLES AND MISCELLANEOUS INFORMATION.

The following tabulated form shows the order of succession of the various stratified rocks with their usual thicknesses.

Groups.							Strata.				Thickness in Feet.
		RECENT					1	Modern Deposits.
		PLEISTOCENE					2	Drift and Gravel Beds			20 to 100
							3	Mammaliferous Crag			10 to 40
		PLIOCENE					4	Red Crag			30
CAINOZOIC, OR							5	Suffolk (Coralline) Crag			30
TERTIARY.		MIOCENE					6	Faluns (Touraine) Molasse Sandstones			6000
							7	Hempstead Series			170
				Upper			8	Bembridge Series			110
							9	Headon Series			200
		EOCENE		Middle			10	Barton Beds			300
							11	Bagshot and Bracklesham Series			1200
				Lower			12	London Clay and Bognor Beds			200 to 520
							13	Woolwich Beds & Thanet Sands			100
							14	Maestricht Beds			110
							15	Upper Chalk			300
							16	Lower Chalk and Chalk Marl			400
		CRETACEOUS					17	Upper Greensand			130
							18	Gault			100
							19	Speeton Clay			130
							20	Lower Greensand			250
		WEALDEN					21	Weald Clay			150
							22	Hastings Sands			600
		PURBECK					23	Purbeck Beds			150
		UPPER					24	Portland Rock and Sand			150
		OOLITE					25	Kimmeridge Clay			400
							26	Upper Calcareous Grit			40
MESOZOIC, OR		MIDDLE					27	Coralline Oolite			30
SECONDARY.		OOLITE					28	Lower Calcareous Grit			40
							29	Oxford Clay			400
							30	Kellaways Rock			30
							31	Cornbrash			10
							32	Forest Marble and Bradford Clay			50
		LOWER					33	Great Oolite			120
		OOLITE					34	Stonesfield Slate			9
							35	Fullers’ Earth			50 to 150
							36	Inferior Oolite			80 to 250
							37	Upper Lias Shale			50 to 300
		LIAS					38	Marlstone and Shale			30 to 200
							39	Lower Lias and Bone Beds			100 to 300
		TRIASSIC, or					40	Variegated Marls or Keuper			800
		NEW RED					41	Muschelkalk
		SANDSTONE					42	Red Sandstone or Bunter			600
		PERMIAN or					43	Red Sand and Marl			50
		MAGNESIAN					44	Magnesian Limestone			300
		LIMESTONE					45	Marl Slate			60
							46	Lower Red Sandstone			200
							47	Coal Measures			3000 to 12,000
		CARBONIFEROUS					48	Millstone Grit			600
							49	Mountain Limestone			500 to 1400
							50	Limestone Shales			1000
PALÆOZOIC, OR		DEVONIAN or					51	Upper Devonian
PRIMARY.		OLD RED					52	Middle Devonian			3000 to 8000
		SANDSTONE					53	Lower Devonian and Tilestones
							54	Ludlow Rocks			2000
				Upper			55	Wenlock Beds			1800
							56	Woolhope Series			3050
		SILURIAN		Middle			57	Llandovery Rocks			2000
							58	Caradoc and Bala Rocks			5000
				Lower			59	Llandeilo Rocks			4000
							60	Lingula Flags			8000
		CAMBRIAN					61	Longmynd and Cambrian Rocks			20,000
		METAMORPHIC						Clay Slate, Mica-Schist.
AZOIC.								Gneiss, Quartz Rocks.
		IGNEOUS						Granite.

The Quantity of Excavation in Wells for each Foot in Depth. (Hurst.)
Diameter of Excavation.		Quantity.
ft.	in.	cubic yards.
3	0	·2618
3	3	·3072
3	6	·3563
3	9	·4091
4	0	·4654
4	3	·5254
4	6	·5890
4	9	·6563
5	0	·7272
5	3	·8018
5	6	·8799
5	9	·9617
6	0	1·0472
6	3	1·1363
6	6	1·2290
6	9	1·3254
7	0	1·4254
7	3	1·5290
7	6	1·6362
7	9	1·7472
8	0	1·8617
8	6	2·1017
9	0	2·3562
9	6	2·6253
10	0	2·9089
10	6	3·2070
11	0	3·5198
12	0	4·1888

The Measure in Gallons, and the Weight in Pounds, of Watercontained in Wells, for each Foot in Depth.
Diameter.		No. of Galls.	Weight.
ft.	in.
2	0	19·61	196·1
2	6	30·56	305·6
3	0	43·97	439·7
3	6	60·00	600·0
4	0	78·19	781·9
4	6	98·87	988·7
5	0	122·23	1222·3
5	6	147·96	1479·6
6	0	175·99	1759·9
6	6	206·59	2065·9
7	0	239·05	2395·0
7	6	275·49	2754·9
8	0	313·43	3134·3
8	6	353·03	3533·0
9	0	395·42	3954·2
9	6	441·71	4417·1
10	0	489·93	4899·3

Brickwork. The Number of Bricks and Quantity of Brickwork in Wells for each Foot in Depth. (Hurst.)
	Half-Brick Thick.			One Brick Thick.
	Number of Bricks.			Number of Bricks.
	Laid Dry.	Laid in Mortar.	Cubic Feet of Brickwork.	Laid Dry.	Laid in Mortar.	Cubic Feet of Brickwork.
1·0	28	23	1·6198	70	58	4·1233
1·3	33	27	1·8145	80	66	4·7124
1·6	38	31	2·2089	90	74	5·3015
1·9	43	35	2·7979	112	92	6·4795
2·3	53	44	3·0926	122	100	7·0686
2·6	58	48	3·3870	132	108	7·6577
3·0	68	57	3·9760	154	126	8·8357
3·6	79	65	4·5651	174	142	10·0139
4·0	89	73	5·1541	194	159	11·1919
4·6	100	82	5·7432	214	176	12·3701
5·0	110	90	6·3322	234	192	13·5481
5·6	120	98	6·9213	254	209	14·7263
6·0	130	107	7·5103	276	226	15·9043
6·6	140	115	8·0994	296	242	17·0825
7·0	150	123	8·6884	316	260	18·2605
7·6	160	131	9·2775	336	276	19·4387
8·0	170	140	9·8665	358	292	20·6167
8·6	180	148	10·4556	378	308	21·7949
9·0	191	156	11·0446	398	326	22·9729
10·0	212	174	12·2227	438	360	25·3291

Good bricks are characterized as being regular in shape, with plane parallel surfaces, and sharp right-angles; clear ringing sound when struck, a compact uniform structure when broken, and freedom from air-bubbles and cracks. They should not absorb more than one-fifteenth of their weight in water.

After making liberal allowance for waste, 9 bricks will build a square foot 9 inches thick, or 900, 100 square feet, or say 2880 to the rood of 9-inch work, which gives the simple rule of 80 bricks = a square yard of 9-inch work.

The resistance to crushing is from 1200 to 4500 lb. a square inch; the resistance to fracture, from 600 to 2500 lb. a square inch; tensile strength, 275 lb. a square inch; weight, in mortar, 175 lb. a cubic foot; in cement, 125 lb. a cubic foot.

Compressed bricks are much heavier, and consequently proportionately stronger, than those of ordinary make.