Page:Encyclopædia Britannica, Ninth Edition, v. 4.djvu/511

Rh BONDING.] BUILDING 401 under fig. 2, at g, is the plan of a 14-inch wall, showing the headers on one side, and the stretchers on the other, and at h is the plan of the course immediately above it, in which the headers and stretchers are inverted ; at k and i are shown in the same manner the plans of two courses of glish an 18-inch wall. This is called English bond. Thicker i il- walls are constructed in the same manner by the extension of the same principle. &amp;gt;scrs. But a brick being exactly half its length in breadth, it is impossible, commencing from a vertical end or quoin, to make a bond with whole bricks, as the joints must of necessity fall one over the other. This difficulty is obviated by cutting a brick longitudinally into two equal parts, which are called half headers. One of these is placed next to a whole header, inward from the angle, and forms with it a three-quarter length between the stretchers above and below, thus making a regular overlap, which may then be preserved throughout ; half headers so applied are technically termed closers, and are shown next the upright angle of the wall fig. 2, and the first joints inwards from the square ends by the headers in the plans at g and li. A three-quarter stretcher is obviously as available for this purpose as a half header, but the latter is preferred, because, by the use of it, uniformity of appearance is preserved, and whole bricks are retained on the returns. In walls of almost all thicknesses above 9 inches, to preserve the transverse, and yet not destroy the longitudinal bond, it is frequently necessary to use half bricks ; but it becomes a question whether more is not lost in the general firmness and consistence of the wall by that necessity, than is gained in the uniformity of the bond. It may certainly be taken as a general rule, that a brick should never be cut if it can be worked in whole, for a new joint is thereby created in a construction, the difficulty of which consists in obviating the debility arising from the constant recurrence of joints. Great attention should be paid to this, especially in the quoins of buildings, in which half bricks most frequently occur ; and there it is not only of consequence to have the greatest degree of consistence, but the quarter bricks used as closers are already admitted, and the weakness con sequent on their admission would only be increased by the use of other bats, or fragments of bricks. Imish Another mode of bonding brickwork, which may be 1 1( 1- supposed to have arisen from the appearance of the ends of a wall according to the former mode of arrangement (see e and /, fig. 2), instead of placing the bricks in alternate courses of headers and stretchers, places headers and stretchers alternately in the same course, fig. 3. The plans below this at c and d are of two courses of a 14-inch wall, with their bond, showing in what manner the joints are broken in the wall horizontally as well as vertically on its face. This is called Flemish bond. Closers are also necessary to this variety of bond ; half bricks also will occur in both, but what has been said with reference to the use of them in the former applies even with more force to the latter, for they are more frequent in Flemish than in English, and its transverse tie is thereby rendered less strong. Their occurrence is a disadvantage which every care should be taken to obviate. The arrangements of the joints, however, in Flemish b ond, presenting a neater appearance than that of English bond, it, is generally preferred for external walls when their outer faces are not to be covered with some composition ; but English bond should have the preference when the greatest degree of strength and compactness is considered of the highest importance, because it affords, as we have already noticed, a better transverse tie than the other. &amp;gt; Flemish Mr W. Hosking was the first to notice (in the last edition 11(1 of this work) that what is in England called Flemish bond is unknown in Flanders, and is practised in the British Isles alone. In Flanders, Holland, and Hhenish Germany, which are bricklaying countries, no kind of bond is found but what is known in England as English bond. But it has lately been noticed that the mediaeval brick buildings in the north-east of Germany are worked in Flemish bond, or as it is there called &quot; cross-bond ; &quot; and it is also to be seen at Brussels in work of about the end of the 18th century. Many of the buildings designed by Inigo Jones in England, and perhaps all of those by Sir 0. Wren, are executed in Flemish bond, which name, it has been suggested, might have been derived from the word &quot; flemishing &quot; used by workmen, and thus applied to brickwork as meaning work better &quot; finished off &quot; than the other kind. It has been attempted to improve the bond in thick Herring- walls by laying raking courses in the core between external kone woik. stretching courses, and reversing the rake when the course recurs. This obviates whatever necessity may exist of using half bricks in the heading courses, but it leaves triangular interstices to be filled up with bats, as is shown in Plate XX. fig. 4. This represents the plan of 36-inch or three-brick wall with raking courses at a, between ex ternal ranges of stretchers, and lying on a complete course of headers, and at b a wall of the same thickness herring- boned ; courses of headers would bed and cover this also, and, in the second course above, the raking or herring- boning would be repeated, but the direction of the bricks reversed. It will be seen that the latter demands, in addi tion to the triangular filling in bats at the outer ends of the diagonally placed bricks, half bricks to fill up the central line of interstices, rendering herring-boning more objectionable in that particular, though it has some advan tages over simply raking, or thorough diagonal courses in other points. Neither mode should, however, be had recourse to for walls of a less thickness than three bricks, and that indeed is almost too thin to admit of any great advantage from it. Not second in importance to bonding is, that the brick- Walls to work be perfectly plumb, or vertical, and that every course 1je vertical be perfectly horizontal, or level, both longitudinally and aml transversely. The lowest course in the footings of a brick wall should be laid with the strictest attention to this latter particular ; for the bricks being of equal thickness through out, the slightest irregularity or incorrectness in that will be carried into the superimposing courses, and can only be rectified by using a greater or less quantity of mortar in one part or another, so that the wall will of course yield unequally to the superincumbent weight, as the work goes on, and perpetuate the infirmity. To save the trouble of keeping the plumb-rule and level constantly in his hands, and yet to insure correct work, the bricklayer, on clearing the footings of a wall, builds up six or eight courses at the external angles (Plate XX. fig. 5), which he carefully plumbs and levels across, and from one to the other. These form a gauge for the intervening parts of the courses, a line being tightly strained from one end to the other, resting on the upper and outer angles of the gauge bricks of the next course to be laid, as at a and b, and with this he makes his work range. If, however, the length be great, the line will of course sag ; and it must therefore be carefully set and propped at sufficient intervals. Having carried up three or four courses to a level, with the guidance of tho line, the work should be proved with the level and plumb- rule, and particularly with the latter at the quoins and reveals, as well as on the face. A smart tap with the end of the handle of the trowel will generally suffice to make a brick yield what little it may be out, while the work is so green, and not injure it. Good workmen, however, take a pride in showing how correctly their work will plumb with out tapping. In work which is circular on the plan, both the level and the plumb-rule must be used, together with