14. The iron crow and pickaxe, for breaking and brick-work, and for driving or dividing bricks: to | ground, as well as for beating it solid, before building; adapt it to these different uses, one end is formed like a common hammer, and the other is furnished with a kind of axe; 3. The plumb-rule, Fig. 241, which is a thin rule, six or seven inches wide, with a line and plummet swinging in the middle: its use is to guide the bricklayer in carrying up his walls perpendicularly; 4. The level, Fig. 242, which is ten or In the preparation and cutting of gauged arches, the following articles are used: 15. The banker, Fig 246, a bench from 6 to 12 feet long, from 2 to 3 Fig. 242. twelve feet long, with a vertical rule attached to it, in which a line and plummet are suspended: its use is to try the level of the walls at various stages of the building, as it proceeds, and particularly at the window-sills and wall-plates; 5. The large square, for setting out the sides of a building at right angles; 6. The rod, for measuring lengths, usually five or ten feet long; 7. The jointing rule, about eight or ten feet long, and four inches broad, with which the bricklayers run, or mark, the centre of each joint of the brickwork; 8. The jointer, Fig. 243, an iron tool, shaped like the letter S: it is used with the jointing-rule for marking the joints; 9. The Fig. 243. Fig. 244. Fig. 245. of wood about half an inch thick, with at least one curved edge, rising about one inch in six feet, for drawing the soffit line of straight arches. When the lower edge is curved, it rises about half that of the other, or about half an inch in six feet, for the purpose of drawing the upper line of the arch, so as to prevent it becoming hollow by the settling of the arch. The upper edge is not always cambered, some preferring it straight. The slip being sufficiently long, it answers the width of many openings; and when the bricklayer has drawn his arch, he delivers it to the carpenter, to prepare the centre for it; 17. The rubbing-stone is a rough-grained stone, about twenty inches diameter, or less. It is fixed upon one end of the banker, Fig. 246, upon a bed of mortar. After the bricks for the gauged work have been rough-shaped by the axe, they are rubbed smooth on the rubbingcompasses, for traversing arches and vaults; 10. stone. The headers and stretchers, in return, which The raker, Fig. 244, a piece of iron, having two are not axed, are called rubbed returns, and rubbed knees, or angles, the points of which are used for headers and stretchers; 18. The bedding-stone, a raking out decayed mortar from the joints of old straight piece of marble, eighteen or twenty inches walls, for the purpose of replacing it with new long, of any thickness, and about eight or ten inches mortar, or, as it is called, pointing them; 11. The wide. Its use is to try the rubbed side of a brick, hod, a wooden trough, shut close across at one end, which must be first squared, to prove whether its and open at the other: the sides consist of two surface be straight, so as to fit it upon the leading boards at right angles to each other, with a long skew back or leading end of the arch; 19. The square, handle projecting downwards from the middle of the for trying the bedding of the bricks, and squaring angular ridge formed by the meeting of the two the soffits across the breadth of the bricks; 20. The sides; this ridge is also partly covered by a cushion bevel, Fig. 248, for drawing the soffit line Fig. 248. of leather, stuffed with wool, to prevent it from on the face of the bricks; 21. The mould, cutting the shoulder of the labourer. The hod is for forming the face and back of the brick, used by the labourer for conveying bricks and mortar in order to reduce it in thickness to its to the bricklayer. To prevent the mortar from proper taper, one edge of the mould sticking, dry sand is strewed on the inside; 12. The being brought close to the bed of the line-pins, Fig. 245, which are of iron, for fastening and brick when squared. The mould has a stretching the line at proper intervals of the wall, notch for every course of the arch; 22. The scribe, that each course may be kept straight in the face and a spike or large nail, ground to a sharp point, to mark level on the bed: the pins have a line attached to the bricks on the face and back by the tapering edges them, of sixty feet to each pin; 13. The rammer, of the mould, for the purpose of cutting them; 23. similar to that of paviours: it is used for trying the | The tin saw used for cutting the soffit lines about one-eighth of an inch deep, first by the edge of the level, | piers ought to be as uniform as possible, for, although the bottom of the trench may be very firm, yet, if it vary in firmness, the piers will settle more in one place than in another, and thus occasion a vertical fracture in the superstructure. Should the solid parts of the trench be under the intended openings, and the softer parts where piers are to be built, on firm ground, arches, not inverted, must be suspended between them; in which case, attention must be paid to the insisting pier, whether it will cover the arch or not; for if the middle of the pier rest over the middle of the summit of the arch, the narrower the pier, the greater should be the curvature of the arch at its apex. When suspended arches are used, the intrados ought to be clear, that the arch may have its full effect. Here, also, the ground on which the piers are erected must be of equal firmness, lest the building be injured by unequal settling, which is much more mischievous than where the ground, from being uniformly soft, allows the piers to descend equally, in which case the building is seldom or never damaged. on the face of the brick, then, by the edge of the square, on the bed of the brick, in order to enter the brick-axe, and to keep the brick from spalting. The saw is also used for cutting the soffit through its breadth, in the direction of the tapering lines drawn upon the face and back edge of the brick, and also for cutting the false joints of headers and stretchers; Fig. 249. 24. The brick-axe, Fig. 249, for axing off the soffits of bricks to the saw cuttings, and the sides to the lines drawn by the scribes. The bricks being always rubbed smooth after axing, the more truly they are axed, the less labour will be required in rubbing them; 25. The templet, used for taking the length of the stretcher and width of the header; 26. The chopping-block, for reducing bricks to their intended size and form, by axing them. It is a piece of rough wood, six or eight inches square, supported on two fourteeninch brick piers; but it varies in size according to the number of men working at it; 27. The floatstone, used for rubbing curved work smooth, such as the cylindrical backs and spherical heads of niches, to take out the axe marks. It is previously brought into a form the reverse of the surface to which it is applied. In the raising of brick walls, it is of great importance to secure a good foundation. Trenches are dug for foundations, and the ground is tried with a crowbar or rammer, to ascertain its soundness. If it appear to shake, it must be bored with a well-sinker's tool, to ascertain whether the shaking be local or general. If the soil be firm, the looser parts, if not very deep, are dug up, until the solid bed is got at. If the ground be not very loose, it may be made good by ramming into it large stones, closely packed together; but if the ground be very bad, it must be piled and planked, and in such cases, concrete is of very great service. In rising ground, the foundation must be made to rise in a series of steps. When the ground is loose in places over which it is intended to make windows, doors, &c., while the ground at the sides on which the piers are to stand is firm, it is usual to turn inverted arches over such intended openings, Fig. 250. This is a necessary precaution Fig. 250. in all cases where the depth of the wall below will admit of it; for the piers in settling will carry the arch with them, and, by compressing the ground, assist in securing the structure. These arches should be turned with great exactness, and their height should be at least half their width. The bed of the In ramming foundations, the stones, previously chopped or hammered, should be laid of a breadth proportionate to the weight intended to rest on them, and rammed closely together with a heavy rammer. The lower bed of stones may in general project about a foot on each side of the wall: on this another course may be laid, so as to bring the upper bed of stone upon a general level with that of the trench, projecting about eight inches on either side of the wall, or receding four inches on each side within the lower course. The joints of every upper course must fall as nearly as possible on the middle of the stones in the course immediately beneath it; a rule to be strictly attended to in every kind of walling; for in all the modes of laying stones or bricks, the object is to obtain the greatest lap one upon the other. In slacking the lime for preparing the mortar for the wall, no more water should be used than is barely sufficient to reduce it to powder, and it should be covered with a layer of sand to exclude the air. It is best to slack the lime in small quantities, about a bushel at a time. When the mortar is about to be used, it should be beaten three or four times, and turned over with the beater, so as to incorporate the lime and sand, a little water being added. In hot and dry weather the mortar may be made much softer than in winter. In dry weather, and for fine work, the bricks should be wetted or dipped in water as they are laid; a precaution not required in damp weather. This wetting causes the bricks to adhere to the mortar, which they will not do if laid dry and covered with sand or dust, in which case they may often be removed without any mortar adhering to them. In working up the wall, not more than four or five feet of any part should be built at a time; for, as all walls shrink directly after building, the part which is first raised will settle before the adjacent part is brought up to it, and the shrinking of the latter will cause the two parts to separate. Unless it be for the accommodation of the carpenter, no part of a wall ought to be carried higher than one scaffold | without having the contingent parts added to it. In carrying up any particular part, the ends should be regularly sloped off, so as to receive the bond of the adjoining parts on the right and left. The strength of brickwork depends on the manner in which the bricks are laid. The practice in England is confined to what is called Old English bond and Flemish bond. In English bond, Fig. 251, a Fig. 251. row of bricks, laid lengthwise on the length of the wall, is crossed by a row with its breadth in this length, and so on alternately. The courses in which the lengths of the bricks are disposed through the length of the wall, are called stretching courses, and the bricks stretchers. The courses in which the lengths of the bricks run in the thickness of the walls, are called heading courses, and the bricks headers. Flemish bond, Fig. 252, which was in bond. The three-quarter bat thus introduced is called a closer. A similar effect might be obtained by introducing a three-quarter bat at the corner of the stretching course, and then the corner header being laid over it, a lap of 2 inches will be left at the end of the stretchers below for the next header, which being laid, the joint below the stretchers will coincide with its middle, and thus form the bond. In a fourteen-inch, or brick-and-a-half wall, Fig. 256, the stretchingcourse upon one side is laid so that the middle of the breadth of the bricks upon the 'opposite side falls alternately upon the middle of the stretchers and upon the joints between the stretchers. Pig 256. Fig. 257. In a two-and-a-half brick wall, Fig. 258, the bricks are laid as shown in Fig. 259. Fig. 252. troduced into England about the reign of William Fig. 253. Fig. 254. Fig. 255. and Mary, consists in placing a header and a stretcher alternately in the same course. The effect is more pleasing than the former, but this mode does not produce so strong a wall. The face of an upright wall in English bond is shown in Fig. 253, and that of Flemish bond in Fig. 254. Fig. 255 is English bond in a nine-inch walling. Mr. Nicholson remarks that, as the length of a brick is nine inches, and its breadth 41, it is usual, to prevent two vertical joints from running over each other, at the end of the first stretcher from the corner, to place the return corner stretcher, which becomes a header in the face that the stretcher is in below, and occupies half its length; a quarter brick is placed on inside, so that the two together extend 6 inches, leaving a lap of 24 inches for the next header, which lies with its middle upon the middle of the header below, and forms a continuation of the The adoption of Flemish bond leads to the frequent splitting of walls; and to prevent it, laths, or slips of hoop-iron, are sometimes laid in the horizontal joints between the two courses. Others have laid diagonal courses of bricks at certain heights from each other. Attempts have also been made to unite complete bond with Flemish facings, for the sake of the improved appearance which the latter gives. In Figs. 261, 262, 263, 264, the interior bricks are represented as disposed so as to unite the two methods, the adjustment of the bricks in one course must depend upon the course beneath, which must be recollected by the bricklayer after he has covered the course with mortar. Even should he keep his attention thus alive, the work is not so strong as English bond, which, if executed with the same attention and neatness as is required by the Flemish, would be equally handsome in appearance. Mr. Nicholson gives the following rules for forming English bond:-1. Each course is to be formed of headers and stretchers alternately; 2. Every brick in the same course must be laid in the same direction; but in no instance is a brick to be placed with its whole length alongside of another; but to be so situated that the end of one may reach to the middle of the others which lie contiguous to it, excepting the outside of the stretching-course, where three-quarter bricks necessarily occur at the ends, to prevent a continued upright joint in the face-work; 3. A wall which crosses at a right angle with another will have all the bricks of the same level course in the same parallel direction, which completely bonds the angles, as shown by some of the preceding Figures. In building a wall, bricks should incline slightly towards the middle of the wall, that one-half of the wall may act as a shore to the other. It was formerly the practice to build pieces of timber, called bond timbers, into the wall, running through its whole length, in order to add to its strength. This method of building walls is objectionable, because if the timber should decay, the wall may fail before any one is aware of the cause of failure. This method of bonding is now almost entirely superseded by the hoop-iron bond, which consists in laying hoop-iron flatwise between the courses. The iron should be slightly rusted, by which its adhesion to the mortar is greatly increased. In winter it is important to preserve the unfinished wall as much as possible from the alternate effects of rain and frost, the one penetrating into the materials, and the other converting the water into ice, which by its expansion bursts, and crumbles the materials. The unfinished wall must therefore be covered with straw, or with a weather boarding in the form of a stone coping, with a body of straw under the wood. the result is 306 cubic feet in the rod. A rod of standard brick-work with mortar, will require 4,500 bricks on an average, allowing for waste, this number depending on the closeness of the joints, and the size of the bricks. The mortar in a rod of brick work will require 1 cwt. of chalk lime, or 1 cwt. of stone lime, and 2 loads of sand with stone lime or 2 loads with chalk lime. The weight of a rod of brick containing 4,500 stock bricks, 27 bushels of chalk lime, and 3 single loads of drift sand, is about 13 tons. The bricklayer's labourer is paid at the rate of two thirds of the bricklayer's wages per day. One labourer is sufficient for a bricklayer when on the ground, but as the work advances in height, more may be required. In common walling, where there are few or no interruptions by apertures or recesses, the bricklayer will lay 1,000 bricks in one day, or complete a rod in about 4 days. There is a method of constructing a wall with a row of posts or quarters 3 feet apart, the intervals of which are filled up with brick-work. This is called bricknogging. It is seldom more than the width of a brick in thickness, and should not be used where thickness can be obtained for a nine-inch wall. After a wall is built, the joints of the bricks on the face are sometimes filled up with mortar, so as to present a regular and neat appearance. This is called pointing, and is of two kinds, in both of which the mortar in the joints is well raked out, and filled up again with blue mortar; but in one kind, called flat-joint pointing, the courses are simply marked with the edge of a trowel. If in addition to this, plaster be inserted in the joints with a regular projection, and neatly pared to a parallel breadth, this is called tuck-pointing or tuck-joint pointing. Groined arches are sometimes made of brick. A groin is the angular curve formed by the intersection of two semi-cylinders or arches. They are raised on centres formed of carpentry work. The turning of a simple arch on a centre requires only care to keep the courses as close as possible, and to avoid the use of much mortar on the inner part of the joints. The difficulty of executing a brick groin arises from the peculiar mode of making proper bond at the intersection of the two circles as they gradually rise to the crown, where they form an exact point. In the meeting or intersecting of these angles, the inner rib should be perfectly straight and perpendicular to a diagonal line drawn on the plan. After the centres are set, the application of the brick to the angle will show in what direction it is to be cut. The sides are turned as in common cylindric vaults. A variety of ornamental brick cornices may be formed by cutting and changing the position of the bricks employed. Others may be formed by chamfer Brick-work is measured by the rod. A rod of brick-work taken from the original standard of 163 feet square, contained in the superficial rod 2724|ing only. square feet, but as the quarter was found troublesome in calculation, 272 superficial feet came to be the standard for brick-work. The standard thickness of a brick wall is one and a half brick in length, so that if 272 square feet be multiplied by 13 inches, VOL. I. Niches in brick-work form the most difficult part of the bricklayer's art. The difficulty arises from the thinness to which the brick must be reduced at the inner circle, as they cannot extend beyond the thickness of one brick at the crown or top, it being 0 usual as well as neatest to make all the courses | requires that its course should remain open fix the standing. purpose. Hence, the erection of a bridge is s hibited. But where the banks are high, and channel comparatively narrow, a bridge may thrown over, as in the case of the Wear, at Batay! Wearmouth, by Sunderland. So, also, the Stra the Menai are passed over by the great Haya road, without impeding the passage of ships tirg the straits. The chief authority in this article has been Nicholson's New Practical Builder, London, 1823. One of the earliest treatises on Bricklaying is contained in the "Mechanick's Exercises on the doctrine of Handyworks," by Joseph Moxon, third Edition, London, 1703. The Author in his Preface seems to think an apology necessary for writing on such humble subjects as "Bricklayery;" but he says:"I see no more reason why the sordidness of some workmen should be the cause of contempt upon manual operations, than that the excellent invention of a mill should be despised because a blind horse draws in it." BRIDGE. An elevated construction upon or over a depression, and between depressed points, probably derived from the word ridge, with the prefix be. Professor Hosking defines a bridge as "a constructed platform, supported at intervals or at remote points, for the purpose of a road-way over a strait, an inlet or arm of the sea, a river, or other stream of water, a canal, a valley, or other depression, and over another road; distinguished from a causeway, or embanked or other continuously-supported road-way, and from a raft, by being so borne at intervals or at remote points." " Aqueducts, for conveying streams of water or canals, and viaducts, for carrying roads or railways, upon the same, or nearly the same, level, over depressions, are practically considered as bridges. One of the most important requisites in a bridge is permanence. It ought to form a portion of the solid road which it connects, so as to combine comparative ease of approach with convenience of passage and agreeableness of design. The whole depression or valley must practically be obliterated in its effect upon the road, by means of the bridge passing from one summit to the other, so that the ordinary traffic may be carried on without interruption. The bridge must also afford facility of passage under it, not only for the stream, but also for the commerce of men and merchandise which are borne along upon the waters. But a bridge is not limited to one particular form, size, proportion, material, mode of construction, arrangement, or design, but is such as circumstances require it to be. Where a stream or body of water occurs in the line of a great public road, so as to interrupt its continuity, some kind of bridge is necessary. In a river, estuary, strait, or arm of the sea, where the banks are wide and low, and where the navigation for vessels with lofty rigging is to be kept free, an ordinary bridge may be impossible, and a floating bridge, such as a passage-raft, or punt, may be all that can be allowed. For example, the great mail-road from the metropolis, through Bristol, into South Wales, is intercepted by the Severn: the river is wide; its banks are low; the water is sufficient for marine navigation, and the trade of the country (1) "The Theory, Practice, and Architecture of Bridges of Stone, Iron, Timber, and Wire; with Examples on the principle of In treating of so extensive and complicated a s ject as that of bridges, the literature of which firm | a library in itself, it will be desirable to divide it sections, by bringing together, first, a few notes : the History of Bridges, chiefly of stone; second, some details respecting the Theory of Brides thirdly, the Practice of Bridge-building; fourts Timber-bridges; fifthly, Suspension-bridges; lastly, Iron, Girder, and Tubular-bridges. SECTION I-HISTORICAL NOTICE OF BRIDGEN The art of bridge-building, like all other usf. arts, was of slow growth, and has shared in al te varied changes of man's social position at differ periods of his history. In a rude state of society, the most obvious and simple bridge is a tree throw across a stream; or, if the breadth of the stres be too great to be spanned by a single tree, a tre on each side of the stream bent down, and the branches twisted together in the middle. Mazz Park observed this method on the rivers in the terior of Africa. Another step in advance is t stretch across a river a number of ropes, made rushes or leathern thongs, secured on the oppos banks between trees and posts, and connected : covered, so as to form a slight bridge. This method is practised in some of the mountainous districts South America. The ropes are formed of thongs c ox-hide, consisting of several strands, about six er eight inches in thickness, and across these, in a transverse direction, sticks are laid, and these are covered with a flooring of branches of trees. In other cases, an ox-hide rope is extended from one side of the river to the other, and is secured to each bank b means of strong posts. On one side is a kind d wheel, or winch, to straighten or slacken the rope. from which hangs, by a clue at each end, a kind d leathern hammock, capable of holding a man. A rope fastened to either clue, and extended to each side the river, is used for drawing the hammock to th side intended. A push at its first setting-off sends it quickly to the other side. Mules are carried over s this way. Another mode of bridge-building is to constract piers of stone, at a short distance from each other, to be spanned by single stones or slabs, or by bears of timber. When this kind of bridge is used for shallow streams, and is composed of rough stones, without mortar, the operation is simple; but in deep and rapid streams, the construction of piers of hewn stone indicates a considerable advance in the usefa' Suspension: Illustrated by 138 Engravings, and 92 Wood-cuts." arts, because a proper foundation for each pier s required. The bridge over the Euphrates at Babylo Weale: London. 1843. |