Page:Encyclopædia Britannica, Ninth Edition, v. 4.djvu/523

MASON-WORK.] BUILDING 471 which are affected by them. An attentive and intelligent workman will, however, make a sound wall with this species of construction, by fitting the stones well together and packing them with as little mortar as possible, yet filling every crevice with it, and carefully bonding through to secure compactness, transversely at the least. Coursed In coursed rubble walling, fig. G, Plate XXI., the line and work. level are used, the work is laid in courses, each course being carefully brought up to the same level in itself, though no attention is paid to uniformity in the heights of the different courses. For this species of walling the stones are generally thoroughly dressed by the workman in the gross before he begins building. He is careful to get parallel beds to them, and he brings the best face of each stone to a tolerably even surface at right angles to the beds ; the ends, too, receive some little attention, and for this purpose he uses an axe in addition to his scabling hammer. The quoins in coursed rubble walling are gene rally built with peculiar neatness and precision, and they are set to serve as gauge courses for the rest. This, when well executed, makes a sound and excellent wall. It presents, however, rather a rough and homely appearance, and in finer works must be covered with stucco or cement, or faced with ashlar. Ashlar. Ashlar is an external rind of gauged stones in equal courses, having tooled or closely-fitting joints to give a wall a neat and uniform appearance ; it is axed, tooled, or rubbed, as may be thought most in character with the structure, or that part of it to which it is to belong. Ashlar stones, or ashlars as they are commonly called, are made of various sizes on the surface, as the char acter of the edifice may require or convenience demand, and vary in thickness from 5 to 8 or 9 inches. Some of the ashlar stones must, it is clear, be used transversely Gnding. as bond stones, or the facing, having nothing to connect it with the wall behind, would soon totter and fall. Bond stones are generally put in alternate courses, with the backing to the jambs of openings, such as windows, and oftener, if these do not recur within a length of 5 or G feet ; the bond stones themselves, too, should not fall in the same vertical chain, except when they are in the jambs of openings, but should break in their alternate courses. Ashlar is commonly set in fine mortar or in putty. It is generally recommended that ashlars should not be made regular parallelepipeds, but run back irregularly to tooth in with the backing, the vertical joints being left open from about an inch within the face of the wall, and the upper surface or bed of the stones made narrower than, though perfectly parallel to, the lower. These things may exert a slightly beneficial influence under some circumstances ; but the mode of construction involved is so radically bad, that unless the backing is set in a quick-setting cement, or is so well packed as to be proof against its general tendency to settle away from the ashlar facing, no method of the kind can materially improve it. A well-compacted wall of coursed rubble, the courses being frequently made up of whole stones and faced with ashlar, may be made tolerably ick back- sound and trustworthy. Brick backing, with ashlar facing, cannot be considered as good, though it has the advantage of not requiring battening and lathing for inside plastering, as the stone-backed wall does. Uncoursed rubble with ashlar has all the disadvantages of both th e preceding, with nothing to recommend it before either of them. A thin inner brick wall, like a hollow wall, is very often necessary, where it is anticipated that the rain will be beaten through the stone-work by the impetuosity of the wind. The settlement of these two kinds of work during the setting of the mortar is so different, that the walls often separate ; or where this is prevented by bond stones, the walls bulge outwards and bear unequally on their base. These evils are best prevented by using as little mortar as possible in the interior parts of the wall, and not raising the wall a great height at a time. In order to give an uniform colour to a stone or ashlar Badigeon. wall, masons mix up pounded chippings of the stone they have used with some lime, salt, whiting, and size, and a little ochre, with which they colour the stone as they clean off the work. It is called badigeon, and is used also on plastered walls, where joints are sometimes drawn in colour to represent stone-work. Small defects in the stone are filled up with the same, or with shell-lac and the pounded stone. There are many different sorts of walling or modes of Local varie- structure arising from the nature of the materials furnished ties - in various localities. That of most frequent occurrence, perhaps, is a manner in which either squared, broken, or rounded flints are used. These depend entirely on the Flints, care with which they are arranged, and on the mortar with which they are compacted, as also on a coursed chain, which is commonly introduced at short intervals of larger stones or of bricks, to act as a bond ; the quoins, too, in this species of structure are generally constructed of dressed Pisd work, stones or of brick. Another sort of building is that of Pise" work, which from its economy as well as its general utility, has been much used in various countries. It consists of merely compressing earth in moulds or cases, whereby houses of two or three stories in height can be raised. Strong earths, with a mixture of small gravel, form the best material. The earth cannot be used when it is either too dry or too wet ; when prepared it is put into the moulds and rammed down. The openings for the doors and windows must be left at the time of building the walls ; and the openings have to be faced with wood for hanging the doors or for inserting the frames. The exterior decora tions are best made of stone or brick; wood will not unite very well with the Pise" ; the flues are also formed of brick work. The exterior should be cemented or rough-casted, which should only be done when the wall is quite dry, or the cement will be cast off by the damp. The walls require to be bonded at the angles by thin rough planks to each course of about 3 feet in height, and the interior walls to be likewise so tied to the main ones. Such work has lasted over a century and a half. It was extensively practised at Lyons and in the south of France during the last century. Several attempts have been made of late years to build Concrete concrete walls for houses, and with much success. The buildings, process is similar to that already described. One patentee has been enabled to produce a cheap material wherewith he has built every part of a house, walls, floors, staircase, and a flat roof, and even the doors, the material being set in an iron frame, thus rendering the house perfectly in combustible. Several such "monolithic doors" have lately been put up in London in place of plate iron doors. Whatever objections lie against bond timber in brickwork Bond apply with equal force at least to the use of it in stone timbers, walls. Hoop-iron bond is not only available in all kinds of stone walling, including the highly- wrought close-jointed kind, but it is invaluable, as it may be used both longitu dinally and transversely as it may in brickwork ; whilst it compels the building mason to bring his work up to a true and fair bed as often as the bond is to be laid in it. Bis- Discharp;- charging arches, it must be evident, are as necessary in and " 6 arches, to stone walls as to walls of brick, and they may be treated much in the same manner. See fig. 10, Plate XX., and fig. 4, Plate XXI. When walls are not entirely of masonry, in the ordinary Uses of course of economic building, stone is frequently used for stone, copings, cornices, string and blocking courses, sills, land ings, pavings, curbs, steps, stairs, hearth-stones and slabs, and chimney-pieces ; to these may be added quoins and

architectural decorations, or dressings for windows, doors,