long. Specimens of some, if not all of these, are included in the fine collection of polished marbles made by the learned Corsi of Rome, an account of which he published; the collection was subsequently brought to England, and is believed to exist at Liverpool. Each specimen it contained is no less than 8 inches Italian long, 4 inches wide, and 2 inches thick, and highly polished on all sides.

1679. Many of the marbles of France and Belgium are extremely beautiful. They are chiefly used in this country for chimney pieces. The following is a list (including others) of those so worked, supplied from one of the Belgian workshops :-Rouge royal; Bleu Belge; Rouge Griotte; French red; Saint Anna; Noir Belge; Noir Belge, second quality; Breccia (Bréche); Breccia and black; Breccia Romana; Breccia rose; Saint Gerard; Sicilian; Sicilian, white veined; Pavonazzo; Statuary; Statuary, second quality; Malachite; Ver de Mer; Black and green; Porphyry; Brocatello; Siena; Siena, second quality; Italian Griotte; Black and gold; Black and gold, second quality; Bardilla; and Sarracolin. Another marble, named Saint Mont Clarie, is a pure black.

1680. The marbles of Spain are likewise very fine, but are not exported. A specimen of the " Emperor's Red," of unusually fine quality, was presented to the Queen by the late Don Pedro, King of Portugal, for the royal mausoleum at Frogmore.

1681. The marbles of the British Islands deserve more notice from the English architect than they have hitherto received. In England there are but few as yet quarried of granular foliated limestone, the greater number of varieties of them belonging to the floetz or secondary limestone. The most remarkable, and perhaps most beautiful, of the English marbles, is that of Anglesea, called Mona marble, and much resembling Verd antique. Its colours are greenish black, leek green, and sometimes purple, irreguJarly blended with white, but they are not always seen together in the same piece. The white part is limestone, the green shades are said to be owing to serpentine and asbestus. The Isle of Man marbles are--I. Black flagstone (Posidonia schist) from Poolvash, the quarries of which have been worked for upwards of two hundred years; and furnished the steps in St. Paul's Cathedral, presented by Bishop Thomas Wilson. 11. Grey marble (encrinital and shelly limestone) from Poolvash, used for tables and chimney ornaments. III. Black marble (lower carboniferous) limestone, from Port St. Mary, extremely hard and durable, taking a good polish; raised in blocks and flags of great size, and used for piers, floorings, and tombstones. IV. Pale marble (carboniferous limestone (from Scarlet. Castle Rushen, nine hundred years old, and other places, are built with this most durable material. V. Spanish Head flagstone (clay schist), Port St. Mary; is a durable material, and used for lintel and gate posts; it is slightly elastic when in thin flags, and can be raised in square slabs of 16 feet. VI. Peel freestone (old red sandstone), from Craig Millin; of this stone a large portion of Peel Cathedral was built in 1226. (Cumming. Isle of Man, &c.)

1681a. The ornamental marbles of Derbyshire are mostly confined to the 1st, 2nd, and 3rd classes of limestones, which are separated from each other by the toadstone, an amygdaloidal trap rock. These marbles are usually distinguished by their colour, as white, grey, dove, blue, black, and russet; or by physical peculiarities, depending mostly on their fossil contents, as bird's-eye, dog-tooth or muscle, entrochal, shelly, and breccia marbl. s. Quarries of blick marble are situated near Ashford, where machinery for cutting and polishing these marbles was first used in 1748. The beds of black marble seldom exceed 7 or 8 inches; it is difficult to be obtained of any considerable surface free from “shakes,” or small veins of white spar. It is also procured at Matlock and Monsaldah. A brown marble, in thin bands of various depths of colour, is called "rosewood," as it presents the appearance of it when polished. It is one of the hardest and most durable of the Derbyshire marbles. A red marble, resembling Rosso antico, is found chiefly near Newhaven, in lumps of no great size. These and other Derbyshire marbles are principally used for inlaying work, as vases, tables, &c., but chimney pieces, columns, &c., are now made at Ashford, Bakewell, Buckland Holiow, and at Derby. This Florentine work, as it is called, is remarkable for fineness of execution and beauty of design, and is almost confined to the county.

16816. A beautiful greyish-black coralloid marble is also found in Derbyshire and in Wales. The corals it contains are of the porous kind, of the most elegant species, lodged at all angles and in all directions, and are in general about one inch and a half long and three quarters of an inch broad. The other species of coralloid marble is equally beautiful and compact, fine, even texture, very hard, of a deep jet black, and capable of a very high polish. It is variegated with species similar to the above, but smaller, and of a less elegant texture; among these it has usually a great number of sea shells, both turbinated and bivalve, the coral and shells being of a pure snow white.

There are

1681c. The North Devonshire marbles are abundant and diversified. varieties of black and white, from Bridestow, South Tawton, and Drewsteignton. Some of the Chudley, Staverton, and Berry Pomeroy, marbles, have a black ground with large veins of calcareous spar traversing it in all directions. The variegated marbles are gene

rally reddish, brownish, and greyish, variously veined with white and yellow, and the coloura are often intimately blended. The South Devonshire marbles, now chiefly worked at St. Mary Church, Torquay, from the Babbacombe limestone, are called after the name of the estate or quarry from whence they are taken, such as the Petiton, Ogwell, Ashburton, Babbacombe, &c. The colours are red, grey, and variegated, of almost every tint. The sizes of the blocks vary from 1 to 10 tons; the ordinary length runs from 4 to 5 feet; 7 to 8 feet is considered as a good length. At Ipplepen are reddish varietics that are extremely handsome. They are of different qualities, as compact, porcellanic, granular, crystalline, shelly, magnesian, pozolanic or water, stinking or swine. The Bartons quarry

at Ipplepen, belonging to Mr. Field, of Parliament Street, is worked at 80 to 100 feet in depth; the lowest beds are about 8 feet thick, and of a mottled character, being dark red and white in colour; the deposit over it is streaky and lighter in colour. Blocks of 18 feet square are now conveyed to London. This quarry has lately supplied the monolithic polished shafts for the forty columns (18 out of one block), each 12 feet 3 inches in length, and 18 inches diameter on the fillet, with many others, for the new building of the National Provincial Bank of England, in Bishopsgate Street. The bases are of Irish black marble, and the caps of the cream-coloured Huddlestone stone. In the corridor of the new Freemasons' Hall are four columns, two being from the Bartons quarries, and two of Languedoc marble: eight others are placed in the coffee-room of the Charing Cross Hotel. The limestones of Plymouth are not so fine. They are of two sorts; one, an ash colour shaded with black veins; the other blackish grey and white, shaded in concentric spots interspersed with irregular red spots; or black with white veins about a quarter to an inch in width.

1681d. Serpentine, "beyond all question, the most beautiful of the ornamental stones of this country" (Hunt), is chiefly found in the sea-bound peninsula called the Lizard, the most southerly land in Great Britain. This rock, with another called diallage, constitute nearly half of the Lizard peninsula. Serpentine has evidently been under the influence of heat. At one spot it seems to shade off into the hornblende slate in which it is embedded; at another, it has every appearance of having been thrust up among the hornblende slate. Sir Henry de la Beche wrote, many years since, that serpentine ought to be employed for decorative purposes. He named Landewednack, Cadgwith, Kennack, Cove, and Goosehilly Downs, as four sites whence beautiful specimens might be obtained, varying in colour, as, an olive green base striped with greenish-blue steatite veins; another specimen, very hard, with a reddish base studded with crystals of the mineral called diallage, which when cut through and polished, gives forth a beautiful metallic green glitter, heightened still further by the reddish tint of the mass in which it is embedded. To the Exhibition of 1851, Penzance sent fine specimens in all kinds of ornaments. The blocks are small, but sometimes they have been obtained 7 feet in length and 4 or 5 tons in weight; the largest was 8 feet long, 3 feet wide, and 24 feet thick; from 2 to 3 feet long is the usual size. The best blocks are worth from 5 to 10 guineas per ton, according to their weight, the larger the size the higher is the value in an increasing proportion. Chemically, steatite and serpentine differ little from each other, and as they are quarried in juxtaposition, specimens of both kinds are selected for use; but serpentine being much harder and more richly coloured, is appropriated to the larger articles.

1681e. In the Builder of 1865, p. 877, it is stated that serpentine is not a marble, but a tale containing a tolerable quantity of chromate of iron. It is sometimes good for external ornamentation, but never when it has the white streaks so commonly seen in it. Hunt's Handbook to the 1851 Exhibition, gives the following analysis of serpentine obtained at the Lizard: ---Magnesia, 38 68; silica, 42.50; lime and alumina, 2·10; oxide of iron, 1 50、 oxide of manganese, 10; oxide of chromium, 0.30; the colouring matter is probably a combination of chromium, iron, and manganese. In his Handbook to the 1862 Exhibition, it is called a hydrated silicitate of magnesia, composed of silica, 43 ·64; magnesia, 43·35; and water, 13.01 = 100. Besides the supply from the Lizard, it is obtained in Anglesea, Portsoy in Banffshire, Unst and Fetlar in Scotland. The "green marble," or serpentine, of Connemara, is noticed among the Irish marbles. This material is sawn by steam power with sand and water; and when brought into the form required, it is ground, turned, rubbed, and polished until it presents a beautiful glossy surface, said to be capable of resisting grease and acids, which is not the case with marble in general.

66

1681f. It is said that two brackets of old monuments in Westminster Abbey; the panelbordering of the monument erected to the memory of Addison; the brackets of a chimneypiece at Hampton Court, are all carved in serpentine, and the present condition of these specimens shows the durability of it. Equal to granite in durability," is the statement made in advertisements, but probably some further time must elapse before such a statement can be endorsed, though it may be allowed that it appears to stand atmospheric influences reinarkably well. Experiments on the strength of serpentine have been noticed in par. 1502g. Therein is mentioned a shaft of Poltesco grey-green Devonshire serpentine, one of the weakest examples, which went across and not with the vein: the latter running

In the line of the diameter. The green serpentine has been used lately on the outside of some offices in Cornhill; and the red quality in 1853 in Leicester Square.

1681g. Purbeck, Petworth, or Sussex marble, is the name of a material common to Derbyshire, Dorsetshire, the Isle of Wight, Kent, Surrey, and Sussex. It is found at Dinton, near Aylesbury, and it occurs at Boulogne and at Beauvais, in France. In some places, as in the most westerly quarries near Corfe Castle, and at the top of the Isle of Portland, the Purbeck stone is so highly coloured and fine-grained, that it is chiefly identified as belonging to the fresh water deposits by the fossils it contains. In general, the stone may be said to be fine grained in the quarries north and west; while in those approaching the east the pattern is larger, the shells well defined, and scarcely any of them broken; the marble from this district is therefore handsomer, and more in request for ornamental purposes. Purbeck was well known for its quarries during the middle ages, when the marble was in great request for decorating the clustered shafts and sepulchral tombs, and for pavements, in churches. At the present time, there is scarcely sufficient demand to keep more than a few men at work, and this at Woody-hyde, near Corfe Castle, where the genuine material or Purbeck marble can be obtained, and that quarry is a hole more than a quarry. It has been stated that, during the middle ages, this material was also obtained from quarries at Parham Park, six miles north-east of Arundel, but there are now no traces of it left on the surface.

1681h. All varieties of Purbeck marble contain a large proportion of clay in their composition, which is one chief cause of their perishable nature. In the interior of buildings the moisture in the air will be condensed, and absorbed into the argillaceous portion of the marble. While this process is going on, the lustre of the polish is gradually diminished, the colour is altered, its hardness and cohesion destroyed, until the surface is completely changed to a dul! earthy appearance, and decay results, which will be facilitated in proportion to the amount of clay contained in a given mass. When, as in small columns, this material is placed with the planes of lamination in a vertical position, there results another and a greater tendency to decay. The clustered columns in the Temple church, though renewed in 1840-42, had already lost much of their polish in 1853, a preliminary stage towards decay. The large ancient columns supporting the clere-story at Westminster Abbey, have now scarcely a trace left of their original surface. (C. H. Smith, Transactions, Institute of British Architects, 1853). As already stated, this sort of marble is obtained in Kent, where it is also known as Bethersden marble, and likewise as Lovelace marble, obtained near Ashford. In the east and west sides of the new quadrangle of St. John's College, Oxford, are sixteen entire columns of " Bletchingden marble," which were put up in 1631-35. It may be seen in Hythe Church and in some of the neighbouring churches, where it is often varnished in lieu of being polished. The Purbeck marble columns used in Lincoln Minster, in 1186-1200 are asserted to have been worked up by vinegar.

1682. Of the Scotch marbles the principal are the Tiree, of which there are two varieties, red and white. The Iona, whose colours are a greyish white and snow white, sometimes intermixed with steatite, giving it a green or yellow colour in spots and known under the name of Jona or Icolmkill pebbles. It does not take a high polish. The Skye marble, of greyish hue, with occasionally various veins. The Assynt varieties of white, of grey, and dove colour. Glen Tilt marble, white and grey, with occasionally yellow and green spots. Marble of Balliculish, of a grey or white colour, and capable of being produced in considerable blocks. Boyne marble, grey or white, and taking a good polish. Blairgowrie, in Perthshire, of a pure white colour, fit, it is said, to be employed in statuary and for architectural purposes; and Glenavon, a white marble, said by Williams (Natural History of the Mineral Kingdom) to be a valuable marble, is not used, from the remoteness of its situation and the difficulty of access to it.

1683. Ireland is rich in marbles. The dark colours vary from jet black to dark dove colour, purple, blue, and grey; the light colours, from the pure snow white to the celined, cream coloured, pink, and light grey. The variegated consist of the serpentine, black and white veined, mottled, and those marked with fossil organic remains. The black marbles, which are those of most value in Ireland, are extensively met with, and belong to the lower limestone. The merchantable beds of the best quality, which have been extensively worked, are met with in the counties of Galway, Limerick, Carlow, and Kilkenny. It is also found in the counties of Mayo and Waterford. The best quarries are considered to be those close to the town of Galway, near the bank of Lough Corrib. It occurs in three beds, varying from about 9 to 12 inches in thickness. One is called the "London bed,” as it supplies most of the black marble exported to London. Blocks are raised of an average size of about 5 to 10 feet in length, and 4 to 5 feet in width; others 20 feet in length can be obtained. Some blocks 16 feet in length were sent over for a staircase for the Duke of Hamilton's seat in Scotland, who was also furnished with landings and solid balustrades worked to a fine polish. Angliham and Merlin Park quarries supply black marble of the very finest description, receiving a high polish. Steps of it were supplied for the porticos at St. Paul's, the staircases at Marlborough House, Hampton Court, and Kensington Palace, under Sir C. Wren, cir. 1700. At Oughterard, the beds contain more

or less silica, rendering them not so valuable. At Kilkenny, it abounds with shells, which become more conspicuous as the marble dries. Kilkenny marble was once extensively employed in Ireland, but the black is now preferred. The polish of black marble, while it is considerably affected by dampness, is much improved and preserved by being kept dry. 1683a. Dark grey and dark mottled grey marbles are met with chiefly in King's county and in several parts of the county of Cork. Near Tullamore, marble is obtained in large blocks capable of receiving a fine polish, and is much used for chimney-pieces and ornamental works. The limestone around Cork produces easy working marble of a light grey or dove colour, and more or less mottled, receiving a good polish. In the primary districts of Donegal, a light grey and bluish grey coloured marble of close grain is found to a great extent; most of it, however, is hard to work from the quantity of silex it contains. The same kind of a bluish tint is very frequent in Connemara. It is compact in texture, but does not always produce a satisfactory polish. White marble occurs in the western portion of county Donegal, differing much from that of Connemara. It is of comparatively casy conversion, and can be obtained in cubical blocks in great quantities; its very coarsely granular texture, however, is prejudicial to it for many purposes; for boldly executed works in sculpture, where the expense of carriage would be avoided, it might be advantageously employed for many purposes; but it will not vie with the marble of Carrara. The Connemara white marble is hard and fine, and the strongest yet found; it cannot, however, be procured in large blocks free from streaks, which pass through the blocks parallel with the beds. At Chevy, near Dungannon, county Tyrone, a very delicate cream coloured marble is obtained, very compact in texture, receiving a high degree of polish, and blocks of great length can be procured. The coarsely crystalline and fossiliferous limestone at Ardbraccan produces light coloured marble of easy conversion.

16836. Of the variegated marbles, the Siena of the best quality is perhaps the most beautiful. It is obtained in several places in King's county; but the best, the veined or mottled Siena, is found near the Seven Churches. It is susceptible of a high polish, and exhibits many bright and distinct colours. Marble of the same character also prevails, having a dove coloured ground, varied or mottled with Siena colour. In the county of Armagh, a Siena, or rather a brownish red marble, is found, containing a great number of fossil shells; several varieties of colour, from a very light reddish brown to a rather dark red, are also met with, more or less marked with shells. At Pallaskenry in the county of Limerick, a dark red and mottled marble is abundant, and has been much used. A red coloured marble, of a compact but slaty texture, occurs in the county of Cork, extending from the city in a narrow seam, for a distance of several miles. It is hard to work and dull in colour at one time it was extensively used.

1683c. The serpentine, or green marble, as it is usually called, of Connemara, in county Galway, is of a dull green colour. Blocks are raised of considerable size, from which slabs can be obtained, at Barnanoraun quarry, near that at Recess; and at Letternaphy quarry, near Clifden; the latter being rather coarse in quality; while at Tievebaun quarry, near Recess, the marble is dark green, very sound, and free from shakes of any kind. Black and white marble, and that of a mottled character, occur near Cork, in the counties of Waterford, Longford, and Kerry; some of the varieties are very fine; that obtained near Mitchelstown is well marked and receives a high polish. The limestone obtained near the Seven Churches in King's county, when polished, produces a good marble of an even grey colour. It is strongly mottled with very numerous fossil organic remains. It is easily worked, and raised from the quarries in thin beds. This marble, in a polished state, has been used in the construction of one of the principal ruins at the Seven Churches; some of the stones retain their polish to this time, while others exhibit decay. Wilkinson, Geology, &c. of Ireland, 1845). A fine purple marble is found at Loughlougner in county Tipperary, which is said to be beautiful when polished. Some of a purple colour, and purple and white intermixed with yellow spots, were to be procured in the islands near Dunkerron in the river Kenmare.

Its tenacity is stated at 6,000 lbs. per square inch, and its crushing weight is also put at

6,000 lbs. per square inch. (Hunt.) (1520g)

SECT. IV.

TIMBER.

1684. The information we propose here to lay before the reader relative to the different species of timber is extracted from Miller's Gardener's Dictionary, Rondelet's Art de Bàtir, Rees's Cyclopædia, and Hunter's edition of Evelyn's Sylva. To give any thing like the information that would satisfy the botanist would be out of place in an architectural work; and we therefore confine our observations to those which will be useful to the student.

1685. OAK. Of this most valuable timber for building purposes Vitruvius (lib. ii. cap. ix.) enumerates five species, which it would now be difficult to identify. That some species of the Quercus of the botanists are more valuable for building purposes than others no doubts exist. Evelyn seems to commend especially the Irish oak, because of its with. standing the efforts of the worm; but it is not easy to ascertain the particular species to which he alludes In the present day the Sussex oak is esteemed the most valuable; a value, according to some authors, derived from the nature of the soil and from good management in the culture, which is an object of no small importance.

1686. Generally, it has been usual to consider England as producing, without difference in quality, but one species of oak; but two sorts are well known to the English botanist, the Quercus Robur and the Quercus Sessiliflora. The former is found throug! out the temperate parts of Europe, and is that most common in the southern parts of England. Its leaves are formed with regular sinuosities, and their footstalks are short, occasionally almost without any at all. It attains a very large size, and the wood is tolerably straightgrained and pretty free from knots, in many instances resembling the German species called wainscot. It is easily split for making laths for plasterers and slaters, and is beyond doubt the best sort for joist, rafters, and other purposes where stiff and straight-grained timber is a des deratum. In the Quercus Sessiliflora, which, though found about Dulwich and Norwood, according to Miller, appears to be the common oak of Durham, and perhaps of the north of England, the leaves have long footstalks, frequently an inch in length, and their sinuosities are not so deep, but are more regular than those of the Robur just described. The acorns are so close to the branches as to have scarcely any stalks. The wood is of a darker hue, and the grain is so smooth that it resembles chesnut. Than the Robur it possesses more elasticity, hardness, and weight, but in seasoning it is subject to warp and split; hence unfit for laths, which in the north of England are rarely of oak. There is no reason for supposing, as has been conjectured, that the oak of the Gothic roofs of the country is of this species, though we are aware of the great durability of the oak in the buildings in the northern part of the island.

1687. The specific gravity of the species first named, that is, the Quercus Robur, may be taken at about 800, and the weight of a cube foot 50:45 lbs. That of the last-named at 875, and the weight of a cube foot at about 5500 lbs. Their cohesive force and toughness are proportionable.

1688. The American species scarcely claim a notice here, because their use in England is, from every circumstance, out of the question. Of the red oak of Canada (Quercus rubra), the only one of which the use could be contemplated, we merely observe, that it is a light, spongy, and far from durable wood, though, in the country, in many instances useful. Its growth is rapid, and it rises to the height of 90 or 100 feet.

1689. There is a species of oak imported from Norway, which has received the name of clapboard, and another imported from Holland, known under the name of Dutch wainscot, though grown in Germany, whence it is floated down the Rhine for exportation. The latter is destitute of the white streaks which cross the former, and is thereby distinguished from it. The use of these woods has latterly much diminished in England. They are both softer than common oak, and the clapboard far inferior to wainscot. They are more commonly used for fittings and fixtures, whereto they are well adapted. In damp situations, oak decays gradually from its external surface to the centre of the tree; the ring on the outside, which it acquired in the last year of the growth of the tree, decaying first; but if the tree be not felled till past its prime, its decay is reversed by its commencement at the centre. An oak rarely reaches its prime under the age of an hundred years; after that period, which is that of its greatest strength, it cannot be considered as fit for building purposes; and, indeed, it may be taken as a rule, that oak before arriving at its maturity is stronger than that which has passed it.

1690. If the architect has the opportunity of selecting the timber whilst in a state of growth, he will, of course, choose healthy, vigorous, and flourishing trees. Those in which the trunks are most even are to be preferred. A mark of decay is detected in any swelling above the general surface of the wood. Dead branches, especially at the top of the tree, render it suspicious, though the root is the best index to its soundness. notion of Alberti (De Re Ædificatoria), of using all the timber in the same building from

The