main ditch. But his principal improvement consisted in extending the covered way and glacis along the whole of the enceinte, and in placing the ravelin with its proper covered way and glacis on the exterior; in consequence of which disposition it would become impossible for the besiegers to breach the bastion by firing along the ditch of the ravelin, while the latter would possess all the advantages attending the greatest possible saliency. The ideas of Bousmard respecting the disposition of the ravelin were adopted by General Chasseloup de Labat, in the works which he executed, by order of Napoleon I., to strengthen the fortifications of Alessandria; and the same engineer constructed a strong polygonal redoubt of earth in each of the places of arms before the flanked angles of the bastions and ravelins, in order to increase the quantity of crossing and reverse fires in front of the works.

The last modification of the bastion system which it will be necessary to mention, is that proposed by Choumara, who, partly to diminish the pressure of the parapets on the escarp revetment, and to render the formation of a practicable breach more difficult, and partly to procure a close fire of musketry into the covered-way, suggests that a terreplein, like the old chemin des rondes, but with a slender breastwork to protect the defenders, should be left on the exterior of the parapets. The same engineer recommends that the flanks of the bastions should be lengthened by continuing them within the line of the curtain, and that they should have a greater relief than the latter, in order that a fire of artillery might be directed over it against the works of the enemy: he proposes also that a glacis of earth should be raised in the main ditch, high enough to mask the foot of the escarp revetment, and prevent it from being battered by a fire of artillery on the crest of the covered way.

As early as 1640, Dillichs, in a work published at Frankfurt, proposed a method of fortifying places, which consists in surrounding them by lines of rampart forming with each other a series of angles alternately salient and re-entering, being in fact a Tenaille system; and, subsequently to the time of Vauban, a few other projects of a like nature have been suggested. The most remarkable of these is that which was published in 1776 by the French General Montalembert, who entitles his method Fortification Perpendiculaire.' Its outline on the plan is a series of the sides of equilateral triangles formed on those of a dodecagon inclosing the place; the re-entering angles being consequently right angles, and, as the general has developed some useful ideas concerning the interior defence of a place, though no existing fortification affords an example of the method, a short description of it may with propriety be given.

Three parallel ramparts of earth, of the form above indicated, and separated from one another by wet ditches, surround the place: the berme at the foot of the first and third is protected by a simple wall, and that at the foot of the middle rampart is covered by a loop-holed gallery on its whole length. Beyond the outer ditch is the coveredway, whose re-entering angles are fortified by strong redoubts. In the re-entering angles of the two interior ramparts are formed casemated batteries, the fires from which would sweep the surface of the ditches in front, in the directions of their lengths; and, within the enceinte of the place, a circular redoubt, or tower, of brick-work, carrying several tiers of guns, is intended to defend the interior rampart, if, at length, it should be forced. The merit of this system is supposed to consist chiefly in the powerful fire which the casemates would afford, as from their situation, they would scarcely be injured by the enemy; in the difficulty which the latter would experience in getting over the detached walls; and in the great force which the defenders, by means of the spacious communications, might bring up to oppose the assailants. During the existence of the first French empire, the celebrated Carnot proposed to restore the balance between the attack and defence of fortresses, which the inventions of Vauban had made to preponderate greatly in favour of the former, by means of powerful sorties from the place and an abundant discharge of stones and balls from mortars fired at considerable angles of elevation; thus annoying the besiegers in their trenches, and either putting great numbers of their men hors de combat, or compelling them to recur to the slow process of blinding their approaches. Adopting, in his method of fortifying places, the proportions of Cormontaingne for the plan of his bastions, but making the whole length of his front of fortification equal to 480 yards, he detached the bastions from the enceinte, which he made to consist of a simple polygonal rampart of earth. In rear of the tenaille between the bastions he placed a fausse-braye, whose exterior side was to be protected by a casemated tower at each extremity; and, behind the gorge of each bastion, he formed a row of casemate vaults, in which the mortars were to be placed for throwing stones, &c. into that work when gained by the enemy. Adopting also the ideas of Montalembert respecting detached walls, he proposed to surround the enceinte by one, which was to be loop-holed in order that a fire of musketry might be made from it, and to construct a similar wall before the faces and flanks of the bastions. The bastions were to be covered by narrow counterguards; a cavalier, or lofty redoubt, in front of the tenaille, was to defend the collateral faces of both bastions and counterguards; large ravelins were to cover the central parts of the fronts of fortification and afford crossing fires on the ground before the bastions; while mortars placed on the faces of the work and on the barbettes at the angles were to discharge their missiles over the parapets. A ditch

surrounds the whole, and its exterior side is made with a gentle slope from the bottom to the level of the natural ground in front, for the purpose of facilitating the sorties; the corresponding facility which the enemy might have for descending into the ditch being disregarded on account of the supposed impossibility of maintaining himself there under the hail of stones and shot from the works.

It was supposed that the detached wall, being covered as before mentioned, would present an impassable obstacle to the assailants; but an experiment made at Woolwich in 1824, proved the possibility of breaching it by a fire of shot and shells, directed over the parapet of the counterguard, from artillery of great calibre, at the distance of 400 yards from the latter work. The efficiency of the vertical fire, as it is called, of stones and shot from the works has also been controverted; and experiments have been made which seem to prove that the momentum acquired by the missiles in their descent would not be sufficient to do serious injury to a man on whom they might fall, if he were protected by a proper head-piece.

We now come to what is variously termed the polygonal, right-lined, German or Prussian system. It has of late years been much adopted by German engineers, but has never yet been tested by an actual siege. Instead of the ramparts of the enceinte being broken up into bastions and curtains, they follow the lines of the polygon and are flanked by projecting masonry works called caponnières, something like Vauban's tower bastions, or Montalembert's casemated batteries, from which they are taken. The lines of defence may be about 300 yards, so that placing the caponnière in the centre of the side of the polygon this may be taken at 600 yards. The caponnière, projecting about 35 yards from the exterior, will contain 12 guns in 2 tiers of casemates on each side, that is twice as many as an enemy can place in a breaching battery against it; and if built with an interior court for ventilation would be about 30 yards in width. The caponnière is covered in front by a simple counterguard, or by a strong ravelin, and its sides flanked by gun casemates in the enceinte, the ravelin being flanked in the same way, or by casemates at its gorge. The detached escarp has commonly been employed in this system, of which perhaps the best example is Fort Alexander at Coblentz.

Besides these already mentioned, many ingenious systems have been advanced at various times, among which may be mentioned one by Lieut. Cook, late Professor of Fortification at Addiscombe College; Mr. Bordwine's system, and, still later, a further development of this latter by Mr. Fergusson. Mr. Fergusson's system has of late received so much notice from the able manner in which he has advocated it, that it would appear to require some description in this place; but in the limits of this article, though some idea might be given, it would be impossible to do it justice; the reader is therefore referred to Fergusson's System of Fortification.' It may be remarked, however, that ingenious as it undoubtedly is, and remarkable as are some of the ideas propounded, it has not attracted any large amount of support from engineers either in England or on the Continent; and though the author appears to attribute this principally to professional jealousy. &c., it must be acknowledged that it could hardly be carried out in its entirety, nor would it be likely to fulfil his anticipations. It is necessary to guard against the idea, in discussing the system, that the Russians employed it, and with such great success, at Sebastopol. This confused idea appears to have originated from the fact that Mr. Fergusson proposes a huge mound of earth divided into numerous parallel ramparts, and that the Russians used earth-works, though the former proposes to sprinkle his ramparts pretty freely with casemates, and the latter used unrevetted earthworks because they could make no other, and followed the ordinary plans which have been followed for centuries in field fortifications or entrenchments; never raising tier above tier of guns, except where occasionally one battery erected behind and on considerably higher ground fired partially over one in front. This may be easily seen by a very cursory inspection of the plans. The immense duration of the siege of Sebastopol is easily accounted for, when we remember that a large and powerful enemy, never numerically much inferior and occasionally superior to that of the allies, was defending in a naturally very strong position one of the largest and best supplied arsenals in the world, from which they obtained guns and ammunition in greater numbers, and of larger calibre, than the allies had, almost to the last, to bring against them; that their rear and communications were open, so that casualties could be replaced; that they had a powerful feet in their well-fortified harbour, and a great number of the ships of which being sunk supplied them with artillerymen; that they had a large army of observation in the field constantly harassing the allies, and threatening, by such sorties as at Inkermann, to raise the siege; and, lastly, that even on the approach of the allies on the south side, they had sufficient permanent works, as the crenelled wall on the west, the central bastion, the Malakoff tower, &c., with their ships, to make a coup de main hazardous, if not impracticable, and thereby by obliging the allies to make batteries and bring up guns to destroy these, giving themselves time, which they certainly availed themselves of, to erect counter batteries and perfect their defences.

It is scarcely probable that any existing fortresses will be demolished for the sake of the advantages which would result from a re-construction according to any of the methods which have been proposed since the time of Vauban; but, on any future occasion which may

present itself for fortifying a town or military post of importance, it may be found convenient to adopt some improvements in the construction of the works. Thus, the general system of Vauban, with the modifications proposed by Cormontaingne, being retained as the basis, casemates, like those of Montalembert, might be formed in the re-entering angles of the enceinte or tenailles, and detached walls or galleries for musketry in some of the dry ditches: detached ravelins, as proposed by Bousmard, may be constructed beyond those of the ordinary kind, in order to prevent the enceinte from being breached at the first crowning of the glacis; and a direct defence of the covered way may be obtained from galleries formed within, or on the exterior of, the parapets along the faces of the works.

In the open attack of a fortified place it is evident that the loss of life would be so much the greater as the defensive works are stronger and better combined; and, in consequence, the necessity of making the approaches under cover to the last moment of the siege, would become more urgent.

For the works occasionally constructed beyond the glacis of a fortress, see FLECHE, HORN-WORK, LUNETTES, and TENAILLONS.

Of the works which fall under the denomination of field-fortifications, BRIDGE-HEADS have been already mentioned; REDANS, REDOUBTS, and STAR-FORTS are described under those words; and the combinations of works which serve for the protection of armies, that is, Field Fortification, under LINES OF ENTRENCHMENT. Small forts with bastions are frequently employed in field-fortifications: their plan is similar to that of the enceinte of a fortress; but they differ from the latter in their size, in having low relief, and in the sides of their ditches being unrevetted, or only faced with sods. The limits of an article such as this, will only permit of the most cursory notice of this complicated and intricate subject: the reader is therefore referred for further particulars to the standard works, such as Bousmard's Essai Général de Fortification;' Dufour's Mémorial pour les travaux de guerre;' Carnot, 'De la Défence des places fortes;' Sir John Jones' 'Sieges in Spain;' Belma's 'Sieges in Spain;' St. Paul's Traité de Fortification; Aide Mémoire (English) to the Military Sciences; Capt. Macauley, R.E., on Field Fortification; Lieut.-Col. Jebb, R.E., Treatises on Defending Outposts,' and 'The Attack ;' Straith's 'Fortification,' revised and re-arranged by Cook and Hyde, 7th edition, &c. FORTUNE (Fortuna), in the Roman mythology, was a goddess who was supposed to dispose, at her caprice, of the destinies of men;

Fortune. From the statue in the British Museum. corresponding in a great measure to TYCHE of the Greeks. This deity did not figure in the more ancient systems of theosophy; Homer does

not mention Fortune in the Iliad, but refers the events of this world to the decrees of Jupiter and of Fate. Fortune however was worshipped in Italy of old; by the Etruscans at Volsinii, under the name of Nursia; by the Latins at Præneste; and by the Volsci at Antium, where a splendid temple was dedicated to her, in which a sort of oracles was delivered. She had several temples at Rome. As directing the events of life she was represented with a rudder; with a ball as typical of the instability of fortune; and with a cornucopia and occasionally with the modius as diffusing abundance and prosperity. We give an engraving of a statue of Fortuna, in which all these attributes are united: the original, a small but very graceful marble statue (3 feet 1 inch high) is in the Third Greco-Roman Saloon of the British Museum. (Lactantius, Instit. i. 29; Horace, Od. i. 35; Martial, v. ep. 1.)

FORUM, a large open space in ancient Roman cities (corresponding to the Agora of the Greeks), usually surrounded with public buildings, where the citizens met to transact business, and where, previous to the erection of Basilica, causes were tried. From this last circumstance the word forum is used metaphorically for a place of justice. Nardini is of opinion, though without any show of authority, that the first forum, or Forum Romanum, at Rome, was placed on the Palatine Hill. The Greeks made their Agora square, with a double colonnade, or ambulatory, above and below; but in Italy the width of the forum was made less than the length by a third, and the columns set wide apart, as the gladiatorial shows were formerly given in the forum. (Vitruvius, lib. v. 1.) The Roman fora were of two kinds, Fora Civilia and Venalia: the former were for law and political affairs, the latter for the purposes of trade. Rome contained nineteen fora of importance, the Forum Antonini, Archemorium, Argentarium, Augusti, Boarium, Cæsaris, Cupidinis, Nervæ, Olitorium, Piscarium, Piscatorium, Pistorium, Romanum, Sallustii, Suarium, Tauri, Trajani, Transitorium, and Vespasiani. Of these the Forum Romanum, Nervæ, Trajani, Boarium, and Piscatorium, alone retain any traces of the splendid edifices with which they were once adorned. The Forum Romanum is situated in a narrow valley, not far from the Tiber, between the Palatine and Capitoline Hills. It sweeps round towards the Fora of Cæsar and Augustus, which are between it and the larger Fora of Nerva and Trajan, all which, looking at their relative situations, were no doubt connected with it on the north. On the south it extended nearly to the Fora Boarium and Piscatorium, which were near the Pons Palatinus, now called Ponte Rotto: its exact limits are, however, uncertain. It was decorated with temples, statues, basilicæ, curiæ, rostra, triumphal columns, and arches, which usurped the place of shops, schools, and even private houses, that originally stood in this forum. In the forum were the rostra, or pulpits, decorated with the beaks of ships, whence the orators harangued. According to Appian, the rostra were placed in the middle of the forum; and he states that Sulla caused the head of young Marius to be hung up before the rostra in the middle of the forum. Varro, in his fourth book, ' De Lingua Latina,' places the rostra before the curia, which was near the Comitium, so that the orators would stand with their faces towards the capitol; but Plutarch, in speaking of the Gracchi, states the reverse to be the case.

The Comitium was placed near the Curia; three columns of the former, commonly called the Temple of Jupiter Stator, still remain. Nardini places on the side of the Palatine Hill, in succession, the Fabian Arch, Græcostasis, Senalum, Basilica Opimia, Edicula of Concord, Temple of Romulus, Temple of the Dii Penates, Curia Ostilia, near which was the Comitium, Basilica Portia, Temples of Julius Cæsar, and Castor and Pollux. On the side towards the Tiber stood the Temples of Jupiter Stator, Temple and Atrium of Vesta, Basilica Julia, house of Lucius Tarquinius, and the Temple of Victory. On the side of the Capitol were the Arch of Tiberius, the temples of Saturn, of Concord, and of Vespasian, the school of Xanthus, the Arch of Severus, which still remains, and the Tullian Prisons. On the north side of the forum were the office of the secretary to the senate, and the Basilica of Paulus Emilius. There are, however, but few remains existing of a small number of these numerous buildings, and the greater part have entirely disappeared. A single monumental column stands near the Comitium, called the Column of Phocas. Besides these buildings, there are remains of the temples of Fortune, Jupiter Tonans, Jupiter Capitolinus, and the Tabularium, though these are perhaps not within the boundaries of the forum. (See plates in Nardini's 'Rome,' vol. ii., lib. v., c. 1.) A very beautiful restored view of the Forum Romanum was made by Mr. C. R. Cockerell, R.A., and a reduced view was engraved and published, with his permission, in the second volume of the Pompeii,' published by the Society for the Diffusion of Useful Knowledge, to which we refer our readers for an accurate notion of the splendour of the accumulated architecture of the Forum and the Capitol, and its vicinity.

The forum at Pompeii was constructed in the Greek style, and has many Greek features. It is oblong, surrounded on three sides with rows of columns, forming, with the advanced columns of the various buildings, a colonnade or ambulatory; above this there was a second ambulatory, if we may judge from the remains of stairs at several places at the back of the colonnade. The fourth side of the forum is inclosed with two arches placed on each side of a large hypethral temple, called the Temple of Jupiter. On the west side are the prisons and the granary

1, 1, Curia; 2, Ærarium; 3, Chalcidicum; 4, Temple of Mercury; 5, Senaculum; 6, Pantheon; 7, Temple of Jupiter; 8, Prison; 9, Granary; 10, Temple of Venus; 11, Basilica.

been determined, the Chalcidicum [CHALCIDICUM], the Temple of Mercury, the Senaculum, and a building supposed to be a large eatinghouse, generally known by the name of the Pantheon, in front of which are the Taberna Argentariæ. The enclosed area of the forum

Construction in wood and stone of the aræostyle portico of the Forum.
a, holes for the joists of the upper floor.

was paved with large square pieces of marble, and the sides of the area were adorned with statues. Opposite the curiae and a short way from

ARTS AND SCI. DIV. VOL. IV.

them is a small triumphal arch. The forum was closed at night with iron-barred gates, and it does not appear that chariots were admitted into it, as the pavement of the streets terminates at the back of the colonnade. The columns of the ambulatory are of the Greek Doric order, and were being restored in the same style, though with better materials, at the time the city was destroyed. The columns were aræostyle, and the architraves were most probably of wood, as we may infer from their being destroyed, while the frieze and cornice of stone remain.

FOUGASS, a small military mine, formed by sinking in the ground, to a depth not exceeding 10 feet, a box of powder, or one containing two or more loaded shells. The train of powder by which it is to be fired is contained in a linen tube, and this is frequently protected by being placed in a case of wood. A trench is cut in the ground to receive the train, but it is subsequently filled up.

Fougasses are sometimes employed in the defence of field forts, and then they are formed under the glacis, or on the counterscarp, at the points where the assault is expected: in this case generally the train of powder is conveyed under ground to the counterscarp of the ditch, where the fire is to be applied; but occasionally this is done in the interior of the work, the train being then made to pass under the bottom of the ditch.

Sometimes a fougass is used to destroy a small work, in which case it is sunk within the mass of the rampart or parapet.

A stone fougass or rock mortar is formed by excavating a shaft in the ground at an inclination of about 45, and about 6 feet deep. A charge of powder of 50 or 60 lbs. is placed at the bottom of this, with a shield of wood 6 inches thick placed on it. The charge of stones is then thrown in. There may be about 4 cubic yards of stone, each stone or pebble not being less than half a pound in weight; a sufficient body of earth being placed vertically over the stones to make them take effect in the right direction. The charge is fired as an ordinary fougass.

FOUNDATIONS. The surface which immediately supports a building is technically known under the name of its foundation, whether it be natural or artificial; and from this function arise the laws applicable to this particular branch of the arts of construction, namely, that, howsoever formed, the foundations of a building must not be susceptible of movement of any description whatever, after they shall have assumed the statical condition they were designed to assume when loaded to the fullest extent. It follows from the infinite varieties of the resistances of the apparent portions of the earth's crust under the various forces exercised by a building, that very great differences must prevail in the modes of dealing with foundations; and in addition to the difficulties attending this part of the science, other, and perhaps more serious ones arise from the circumstances under which the foundations themselves may have to be prepared or executed. They may, indeed, either be prepared in the open air, or under water, or without disturbing to any serious extent the natural compressible subsoil; and they may be either wholly or partially natural or artificial. Natural foundations require little description here. They exist wherever the site upon which a building has to be erected is situated upon a homogeneous formation of sufficient thickness to render any lateral displacement of the bearing strata impossible. The only danger, indeed, of this class of foundations would arise from the tendency to such movement, and it therefore behoves the engineer or architect to inquire very carefully into the conditions of substratification, and of subterranean water-flow, which might be likely at any future time to develope changes in the statical conditions of the surface strata. Should there not exist any lower moveable beds, there are few rocks which may not be unreservedly trusted as foundations. Gravels, coarse sands, loams, and clays may equally be adopted, provided they be not unconformably deposited on the edges of a highly inclined basin of a rocky nature. Even soft alluvial deposits, when prevented from spreading laterally, may at times be resorted to as natural foundations; but both in this case, and in the one in which diluvial formations occur on the edge of highly inclined strata, care must be exercised in the manner in which they are used. In fact, any stratum which will support a vertical weight equal to 30 pounds upon the superficial inch without sensible compression, after a month's trial, may be considered fit to serve as the foundation of a building: provided always that there be no subjacent moveable strata. The lower courses or the footings of the building itself must therefore present a bearing surface proportionate to the resistance to compression likely to be met with in the natural foundations. Even when the latter are distinctly susceptible of vertical compression, there is, however, less danger from this cause than from their tendency to lateral displacement, especially when they are of a tolerably uniform character; and it is for this reason that it is essential to isolate the bearing surface of any important structure from any irregular or permeable strata whose particles might be displaced by any natural or artificial changes in the hydrographical conditions of the locality. As very few natural foundations are to be met with whose surfaces are sufficiently level to receive the footings of a building, it has been customary of late years to fill in their depressions (to regularise them, in short) by spreading a bed of concrete over them; and it may be received as a tolerably safe general rule, that every rock, gravel, or clay formation will resist a vertical crushing weight which may safely be brought upon the surface of the concrete itself. Of

N

sequently filled in with rubble or with concrete. It is said that the Indian divers carry on the operations of sinking these linings under great depths of water. A good description of the mode of executing the Indian well foundations will be found in the 'Excerpt Minutes of the Institution of Civil Engineers,' for May 12th, 1857, and in those for February, 1842.

The greatest improvement which has lately been introduced in the method of founding important structures, in situations wherein the natural surface of the ground was not adapted to receive them, is, perhaps, the system adopted in founding the bridges of Rochester, Saltash, of the Quarantaine at Lyons, Macon, Bordeaux, Kiel, and Szegedin. In these cases, large tubes were placed in the positions designed for the piers, and an air-tight lock, or chamber, was formed at the top, through which the workmen and the materials were passed. The earth within the tube was dredged out as far as possible by the ordinary processes; and, the various valves being closed, the water was forced through a syphon pipe by compressing the air in the interior. A pressure of one atmosphere (above that of the external air) was usually found to be sufficient for this purpose; but, in order to prevent any rising of the water, or any blowing of the sand, the air in the interior of the cylinders was compressed to about three atmospheres. The workmen then passed to the bottom of the seating, and removed into buckets, which were extracted through the air-locks, the earth which rose above the edge of the tube; and when subsequently the air in the interior was reduced to its normal pressure, the mere weight of the tube and the machinery upon it caused the tube itself to descend in a manner analogous to the descent of a well-curb. In the Rochester and Saltash bridges the tubes were sunk through the permeable, moveable strata until they reached the rocks able to constitute a natural foundation. In the Szegedin Bridge, however, the tubes were merely sunk so far as to obviate any danger of the undermining of the foundations by the action of the river, and a piled bottom was formed in them to receive the concrete. In some cases the tubes were formed of wrought, in others they were of cast iron. One curious observation was made on the occasion of an accident to a tubular foundation of this description at Macon. A barge drove against a cast-iron tube, and broke it; and on attempting to repair the damage so done, it was found that, although the upper portions of the concrete filling (which had been executed with mortar made of the best hydraulic lime) had set, nevertheless the portions which had been immersed in deep water had not commenced to solidify. It would thence appear that there are some hitherto unexplained conditions, with respect to the solidification of mortar under great hydraulic pressure, to which the attention of engineers requires to be directed.

The various descriptions of artificial foundations mentioned above, are supposed to be continued to such a height above the water-line of the neighbourhood, as to allow the superstructure to be erected in the ordinary manner. In tidal rivers or in streams exposed to floods and sudden changes of level, it is however often desirable to carry the bottom courses of the substructure to such a depth below the normal water-line, as to obviate any danger from the removal of the sand, or earth beneath them. If the depth requisite for this purpose should not exceed 8 feet, a simple dam of impermeable earth will suffice to protect the works, and to allow the workmen to lay the masonry in the dry. But in such rivers as the Thames, where the tide rises from 14 to 18 feet, it becomes necessary to resort to the use of COFFER DAMS when it is required to carry the springing courses to any considerable depth below the low-water line. A description of these structures has already been given; as also has been given a description of the CAISSONS SO much employed in the course of the last century; but it may here be added that the practice of engineers at the present day is decidedly to avoid the execution of either of these methods of forming artificial foundations, on account of the expense of the former, and of the uncertainty of the latter. The system now most generally adopted is to inclose the site of the intended structure with a close sheeting, to dredge out the interior very carefully, and to fill in the space thus formed with piles or concrete. Evidently the stability of a foundation of this description must depend upon the depth to which the protective sheeting is driven; it must be carried below the extreme range of the scouring power of the river.

Of late years cast iron has been very successfully substituted for wood in the piles and plates, or sheeting, intended to inclose an artificial foundation. Examples of this description of structure are to be seen at the Blackwall Railway Quay, the Victoria Docks, &c.

When buildings are to be erected upon soft compressible peat, and the hydrographical conditions of the district are not likely to be changed, it may suffice to inclose the whole area of the foundations with a pled or plated sheeting, and to replace a portion of the peat by a layer of sharp silicious sand. In fact sand to a great extent acts like an incompressible fluid under a heavy load, and the effort exerted upon one portion of the surface is distributed over the whole, provided the sand be prevented from spreading. Care must, however, be taken that the subjacent peat should not be subject to lateral displacement, and that whatever compression may take place should forcedly take place in a vertical direction. The seatings of some of the German railways, carried over the immense peat bogs of that country, are occasionally thus formed upon pillars of sand, formed by

filling large square holes sunk through the body of the peat itself; and in some other instances holes were bored through the peat, and subsequently filled in with sand.

A method of forming artificial foundations was formerly much resorted to in the neighbourhood of London, and in other analogous positions, in which the superstructure was carried upon timber platforms so designed and put together as to distribute the weight over a very large area. The success of this system depends, firstly, upon the strength of the platform, which must be sufficient to resist the partial actions of the load; and secondly, upon the durability of the platforms themselves. If any change in the conditions of the moisture of the ground should take place, by improved drainage, or otherwise, the timber may rot, and of course the building erected upon it will be dangerously affected. This danger, it may be added, is far from an imaginary or theoretical one; for in the southern districts of London the changes made of late years in the sewerage have so modified the ordinary state of the surface strata, that the old timber platform foundations are generally decaying.

Whatever may be the description of artificial foundations used, or whatever may be the character of the natural foundations resorted to, it is essential that the weight of the superincumbent structure should be distributed in the most regular possible manner, over the whole bearing surface of the foundations. It is for this purpose that the best builders make a practice of carrying the lower courses of their structures, evenly, under all the walls, and of executing them with the largest and most homogeneous materials they can obtain. The footings, as these lower courses are specially called, are made wider than the upper work, and even when large openings have to be made in the elevation, the weight thus thrown upon the piers, by the sides of these openings, is distributed over the whole area of the footings by means of inverted arches. In countries where brickwork is principally used, and where cement is accessible, it is often customary to introduce, immediately above the footings, a deep band of brickwork in cement, which serves not only to tie together the mass of the wall, but also to intercept the capillary action of the materials of the upper wall upon the moisture in the ground. Where, however, this system cannot be carried into effect, it is essential that precautions should be taken to ensure the strength of the masonry in this part of the structure, and to distribute the effort exercised upon any one portion of it over the widest possible area by the use of the largest blocks in the footing courses. These courses, it may be added, should be made to project on either side of the vertical walls, and to present a number of sets-off proportionate to the weight and character of the superstructure. The width or projection of each set-off should in no case exceed the height of the course itself; but perhaps the most important general remark to be made upon this branch of construction is after all that the materials used in the footing courses should be of the hardest and most impermeable descriptions, and those which would be the least likely to decay under the action of alternations of dryness and humidity. The durability of a building in fact depends so much on the measures which may be taken to prevent the absorption of moisture by the foundations, that it is impossible to exaggerate the precautions to be observed in the selection of their materials. [LIMES; MATERIALS FOR BUILDING.]

FOUNDING; FOUNDRY. Founding or casting is one of the mechanical arts which embraces all the operations of reducing ores, and of smelting and casting metals. There are various branches of the art; and some difference prevails in the minor details of the processes -as in iron-founding, brass- and bronze-founding, cannon-founding, type-founding, and bell-founding. The finishing operations of chasing, burnishing, plating, &c., are also parts of the founder's art. Under the names of the chief metals, as well as in such articles as BELL, CANNON, TYPE, &c., various processes of founding are described; in the present article we shall treat of the general features of the art, especially in connection with large iron castings.

It is certain that the art of founding is of very high antiquity. From the passages in the Old Testament referred to under BRONZE, we find that Tubal Cain was skilled in working in metals, and that the arts of metallurgy were known and practised very extensively by the early Israelites. The extent to which metal-working was carried on by the ancient Egyptians, Assyrians, Phoenicians, Greeks, Etruscans, and Romans, and the excellence to which it was occasionally carried in the fine arts, are too well known to need further observation in this place: a general history of it, as a branch of sculpture, has already been given in the article BRONZE, which also contains some notices from the ancient writers on the different methods adopted of solid hammerworking, hammer-work in plates, and casting; as well as on the varieties and composition of metals. In all the practical points of ancient founding our information is however very limited; the writers of antiquity having confined themselves, generally, to a description of finished productions, and leaving us little or nothing by which we can judge of the mode of working.

It appears that furnaces of considerable size, and producing a great tonnage of metal, were constructed in this country as early as the reign of Elizabeth; but it was not till the beginning of the 17th century that there was effected any great change in the character and importance of founding. Prior to that date all the operations of melting, &c., had been performed by means of wood fuel; but the