very high up, or turned to the court. The door of entrance could only be reached by a staircase. Under the keep were usually vaults, or dungeons, for the reception of prisoners. The keep was enclosed in two courts surrounded by walls flanked with towers. The tower at the entrance was called the barbican, and served at once for an outwork and post of observation. The whole fortress was defended by a moat.

The remains of the Norman castles which exist scarcely afford any specimens of early Norman construction, almost all these castles having been besieged, destroyed, and rebuilt, over and over again. The keep of Falaise is perhaps the only castellated remnant of early Norman times. The castle of Gizors, which was built by William Rufus, retains nothing of its original construction. (Anglo

Doorway

Norman). The Anglo-Norman builders bestowed much pains and evinced considerable artistic skill in very elaborately ornamenting the portal entrances to churches in their style of architecture, by a profusion of ornamental mouldings and of sculpture. Very many examples are to be met with in great variety in several of the counties of England, particularly in the counties of Norfolk and Suffolk. The example represented in the annexed engraving is a beautiful spe

cimen taken from the church of St. Botolph, at Cove, in the county of Suffolk.

Domus, a private house occupied by a single proprietor and his family. Doors (Antique). The Greeks in the temple of Minerva Polias, at Athens, and also the Romans in the temple of Vesta, or the Sibyl, at Tivoli, made the doors and windows smaller at top than at bottom: the architrave or dressing always constituted an agreeable decoration when in character with the building. Those of the windows in the Grecian temple have a projection, or what is sometimes termed a knee, at their upper angle; while those of the temple of Vesta, whose apertures have the same form, continue without interruption, and are surmounted by a cornice; but the cornice above the door is separated from the archi

trave by a frieze, while the cornice of the windows joins the architrave. In the temple of Minerva, the architrave of the windows rests only on a plain socle; those of the temple of Vesta rest also on a socle or support, the face of which is sunk. Doors (Modern). There are two doors, designs of Vignola, which offer in their profiles and proportions a happy medium between the antique and modern compositions; and all other designs of this kind are either derived from them, or possess a vague character which renders them unworthy of imitation.

There are breaks in the architrave, as in those of the temple of Minerva Polias; and the termination or lower extremity of these breaks determines the length of the consoles, which gives harmony to the arrangement. These consoles are also placed against a second architrave, beyond which the first projects. The design of the door of the church of St. Lorenzo is more regular. Doorways. In the Gothic, and the

architecture of the middle ages, doorways are striking and important features, affording in the character of the mouldings and ornaments the style and period of the edifice.

Doric Order. The Doric order, says Palladio, was invented by the Dorians and named from them, being a Grecian people which dwelt in Asia. If Doric columns are made

alone without pilasters, they ought to be seven and a half or eight diameters high. The intercolumns are to be little less than three diameters of the columns; and this manner of spacing the columns is by Vitruvius called Diastylos.

The ancients employed the Doric in temples dedicated to Minerva, to Mars, and to Hercules, whose grave and manly dispositions suited well with the character of this order. Serlio says it is proper for churches dedicated to Jesus Christ,

to St. Paul, St. Peter, or any other saints remarkable for their fortitude in exposing their lives and suffering for the Christian faith. Le Clerc recommends the use of it in all kinds of military buildings; as arsenals, gates of fortified places, guard-rooms, and similar structures. It may likewise be employed in the houses of generals or other martial men,-in mausoleums erected to their memory, or in triumphal bridges and arches built to celebrate their victories.

Vitruvius himself makes the Doric column in porticoes higher by half a diameter than in temples; and most modern architects have, on some occasions, followed his example. In private houses, therefore, it may be 16, 16, or 163 modules high; in interior decorations, even seventeen modules, and sometimes perhaps a trifle more; which increase in the height may be added entirely to the shaft, as in the Tuscan order, without changing either the base or capital. The entablature, too, may remain unaltered in all the aforesaid cases; for it will be sufficiently bold without alteration.

The height of the Doric colunin, including its capital and base, is sixteen modules; and the height of the entablature, four modules; the latter of which being divided into eight parts, two of them are given to the architrave, three to the frieze, and the remaining three to the cornice.

In most of the antiques, the Doric column is executed without a base. Vitruvius likewise makes it without one; the base, according to that author, having been first employed in the Ionic order, to imitate the sandal or covering of a woman's foot. Scamozzi blames this practice; and most of the moderns have been of his opinion, the greatest part of them having employed the Attic base in this order.

Dorman tree, a large beam lying across a room; a joist, or sleeper. Dormer window, a window pierced through a sloping roof, and placed in a small gable which rises on the

side of the roof. Dormitory, a sleeping apartment; a term formerly applied to the sleeping-room of the inmates of monasteries and other religious houses. Dormond, a large beam lying across

a room; a joist, or sleeper: same as Dorman.

Doron, a hand-breadth, or palm : among the Greeks, their bricks or tiles were termed tetradoron, four hands' breadth, or pentadoron, five hands broad; the word also implies a gift: hence, probably, the origin of the English word dowry. Dorture, a place to sleep in, a bedchamber. He led us to a gallery like a dorture." Dosel, hangings round the walls of a hall, or at the east end, and sometimes the sides, of the chancel of a church, made of tapestry or carpet-work; used also in churches, and frequently richly embroidered with silks, and gold and silver. Dosel, ornamental and rich stuff for the back of a chair, a throne, or a screen of ornamental woodwork. Double-acting pump, a pump which

lifts and forces water at the same time, by means of a solid piston, and an entrance and exit-valve communicating with each side. Double-beat valve, a valve used in Cornish engines and water-works. It has two beats, or seatings, one above the other; the bottom one is similar to an ordinary circular valve seating; the top one is somewhat less in diameter than the bottom one, and is supported from it by ribs, and forms a cover nearly the size of the inner passage. A shell with two beats to correspond with the seatings shuts the sides; when raised (which requires but httle power, as the fixed cover before mentioned bears nearly all the pressure, its diameter being

nearly equal to that of the shell) the steam or water escapes at the sides both of the top and bottom beat. Double-cylinder engine, a marine engine with two cylinders placed at right angles to the crank-shaft, and at a small distance apart, to give space for the vibration of the rod connecting the crank to the long end of a shaped cross-head, which slides in grooves between the cylinders; the upper ends of the cross-head are connected to the piston-rods. This form of engine is patented by Messrs. Maudslay. Doucine, a moulding, concave above and convex below. Dove-tail, in carpentry, a method of joining two boards together by letting one piece into another in the form of the tail of a dove, when that which is inserted has the appearance of a wedge reversed. Dove-tailing, a method of fastening together two pieces of metal or wood by projecting bits cut in the form of dove-tails in one piece, to fit into corresponding hollows in the other.

Dowel. A round dowel or coak is the piece of timber to which the felloes of a carriage-wheel are united. Dowsing cheeks, in ship-building, pieces fayed across the apron, and lapped on the knightheads or inside stuff above the upper deck. Drabler, a small topsail. Drabs, in salt-works, a kind of wooden box for holding the salt when taken out of the boiling pan. Draft-engine, an engine used for pumping. Drag-bar, a strong iron rod with eye-holes at each end, connecting a locomotive engine and tender by means of the drag-bolt and spring. Drag-bolt, the strong bolt coupling the drag-bar of a locomotive engine and tender together, and removable at pleasure.

Drag-hook and chain, the strong chain and hook attached to the front of

the engine buffer-bar, to connect it on to any other locomotive engine or tender; also attached to the drag-bars of goods-waggons. Drag-link, a link for connecting the cranks of two shafts; it is used in marine engines for connecting the crank on the main-shaft to that on the inner paddle-shaft. Drag-spring, a strong spring placed near the back of the tender. It is attached by the ends to the dragbar which connects the engine and tender, and by the centre to the drag-bar which connects the train to the tender.

Dragon-beams are two strong braces which stand under a breast-summer and meet in an angle on the shoulders of the king-piece. Dragon's blood (colour), a resinous substance brought from the East Indies. It is of a warm semi-transparent, rather dull-red colour, which is deepened by impure air, and darkened by light. There are two or three sorts, but that in drops is the best. White lead soon destroys it, and it dries with extreme difficulty in oil. It is sometimes used to colour varnishes and lacquers, being soluble in oils and alcohol; but notwithstanding it has been recommended as a pigment, it does not merit the attention of the artist.

Drainage of marshes and fen lands.

The steam-engine is used to raise the water above the level of those lands which lie too low to be drained by natural outfall, and also in situations where the fall is not sufficient to carry off the superfluous water in time to prevent damage to the crops.

Mr. Glynn has applied steampower to the drainage of land in fifteen districts, all in England, chiefly in Cambridgeshire, Lincolnshire, and Norfolk. The quantity of land so drained amounts to more than 125,000 acres, the engines employed being seventeen in number, and their aggregate power 870

horses the size of the engines varies from 20 to 80 horses. Mr. Glynn was also engaged in draining by steam power the Hammerbrook district, close by the city of Hamburgh; and in another level near to Rotterdam, an engine and machinery with the requisite buildings have been erected from his plans by the Chevalier Conrad, and the works successfully carried into effect.

In British Guiana the steam-engine has been made to answer the double purpose of drainage and irrigation. Some of the sugar-plantations of Demerara are drained of the superfluous water during the rainy season, and watered during the dry season.

In many of the swampy levels of Lincolnshire and Cambridgeshire, much had been done to carry off the water by natural means, and many large cuts had been made and embankments formed, especially in the Bedford Level, which alone contains about 300,000 acres of fen-land; the Great Level of the fens contains about 680,000, formerly of little value, but now rich in corn and cattle. The general plan is to carry away the water coming off the higher grounds, and prevent it, as much as possible, from running down into the marsh by means of the catchwater drains, leaving the rain alone which falls upon the district to be dealt with by mechanical power. As the quantity of rain falling on the Great Level of the fens seldom exceeds 26 inches in the year, and about two-thirds of this quantity is carried off by evaporation and absorption, or the growth of plants, it is only in extreme cases that 2 inches in depth require to be thrown off by the engines in any one month, which amounts to 1 cubic foot of water upon every square yard of land, or 7260 feet to the acre.

The standard and accepted measure of a horse's power is 33,000lbs.

raised 1 foot high in a minute, or 3300bs. raised 10 feet high in the same time; and as a cubic foot of water weighs 624tbs., and a gallon of water 10lbs., so one horse's power will raise and discharge, at a height of 10 feet, 330 gallons, or 52% cubic feet of water in a minute. Consequently this assumed excess of 7260 cubic feet of water fallen upon an acre of land will be raised and discharged at an elevation of 10 feet in about two hours and twenty minutes. If the quantity of land be 1000 acres of fen or marsh, with the upland waters all banked out, the excess of rain, according to the foregoing estimate, will amount to 726,000 cubic feet. A steam-engine of 10-horse power will throw off this water in 232 hours, or in less than twenty days, working twelve hours a day. This calculation has been found fully supported in practice.

Although the rain due to any given mouth may fall in a few days, yet in such case much of it will be absorbed by the ground; and the drains must be made of sufficient capacity to receive and contain the rain as it falls; besides, in case of necessity, the engine may be made to work twenty hours a day instead of twelve, until the danger be past.

The main drains have generally been cut 74 feet deep, and of width sufficient to give them the required capacity to contain the excess of rain, and to bring the water freely down to the engine. In some instances, where the districts are extensive and their length great, it has been found necessary to make them somewhat deeper.

In all cases where it has been requisite to use steam-power, Mr. Glynn has applied scoop-wheels to raise the water. These scoop-wheels somewhat resemble the undershot wheel of a water-mill, but instead of being turned by the impulse of the water, they are used to lift it,

and are kept in motion by the steam-engine.

The floats or ladle-boards of the wheels are made of wood, and fitted to work in a trough or track of masonry; they are generally made 5 feet in length, that is to say, they are immersed 5 feet deep in the water, and their width or horizontal dimension varies from 20 inches to 5 feet, according to the power of the engines employed, and the head of water to be overcome. The wheel-track at the lower end communicates with the main drain, and at the higher end with the river; the water in the river being kept out by a pair of pointing doors, like the lock-gates of a canal, which close when the engine ceases to work. The wheels themselves are made of cast-iron, formed in parts for convenience of transport. The float-boards are connected with the cast-iron part of the wheel by means of oak-starts, which are stepped into sockets cast in the circumference of the wheel to receive them.

There are cast-iron toothed segments fitted to the wheel, into which works a pinion fixed upon the crank-shaft of the steam-engine. When the head of water in the river or delivering drain does not vary much, it is sufficient to have one speed for the wheel; but where the tide rises in the river, it is desirable to have two speeds or powers of wheel-work, the one to be used at low rate, the other more powerful combination to act against the rising tide. But in most cases it is not requisite to raise the water more than 3 or 4 feet higher than the surface of the land intended to be drained; and even this is only necessary when the rivers are full between their banks, from a continuance of wet weather, or from upland floods. In some instances, the height of the water in the rivers being affected by the tide, the drainage by