When a neater appearance than that of ordinary brickwork is required, soft bricks of even texture, called Cutters or Rubbers, are used, which are cut and rubbed till their surfaces are so regular that a joint 1/32- inch thick may be obtained. Brickwork built of bricks cut and rubbed in this manner is called Gauged Work.

Fig. 174.

## Gauged Work

The simplest form of gauged work is that known as Plain Ashlar - that is to say, plain walls built, or rather faced, with cut and rubbed bricks; for the cut bricks are only used as a facing to a wall, rough brick being used for the interior. Before commencing to cut the facing bricks, therefore, the size of the backing bricks should be measured. Let it be assumed for the sake of explanation that the backing bricks, together with one mortar joint, averages 9 inches in length, 4 1/2 inches in width, and 3 inches in thickness.

## Cutting And Rubbing The Bricks

Each brick is first bedded - that is, it is laid with the frog or wide side downwards upon a. Rubbing stone (Fig. 174), and rubbed with a circular motion, it being tried with a straight edge from time to time, until the surface of the brick is perfectly level. It is next laid face downwards upon the rubbing stone and faced - that is to say, it is rubbed until the face is even and square with the bed, a square being placed with its stock against the bed and the blade against the face, as shown at A, Fig. 175. One end of the brick is then rubbed smooth and squared with the bed and face. The thickness of the brick is now reduced to 3 - 1/32 inches in a Reducing box, shown at B, by filing away the upper surface to the dimension of the box. Every brick is treated in this manner, but if a brick is to be a stretcher the length is now reduced to 9 - 1/32 inches - that is to say, to the average length of the backing bricks less the thickness of one joint in the gauged work. This operation is performed by laying the bricks two at a time bed downwards in a box the internal length of which is 9 - 1/32 inches, with the squared ends flat against the ends of the box, as shown at C, Fig. 175. The projecting ends of the bricks are then cut off with a Bow saw run down the open ends of the box, and if necessary the cut end is trimmed with a file. The box, which is technically termed a Lengthening box, although its use is actually for shortening the bricks, has the edges upon which the saw runs bound with sheet iron for protection. The blade of the saw is composed of two lengths of No. 16 B.W.G. mild steel wire twisted as shown to a larger scale on B, Fig. 185.

If the brick is to be used as a header it is treated similarly to a stretcher, save that the length need not be reduced, the backing bricks being cut with a trowel to fit the facings; but the width must be reduced to 4 1/2-1/32 inches in a box whose internal height is of this dimension, as shown at D, Fig. 175.

Fig. 175.

## Setting Gauged Work

Bricks in gauged work are usually set in lime putty mixed to the consistency of cream, and strained through a sieve with about 400 meshes to a square inch into a Putty tub, E {Fig. 175). This tub usually has a capacity of about one cubic foot. Each brick is taken up, and the faces to be bedded or jointed are just touched upon the surface of the putty, when an amount sufficient to form the mortar joint will adhere to them. The putty should be constantly stirred to prevent the lime from settling. The bricks are then placed carefully into position upon the wall, the backing being built up simultaneously with the gauged work. Cement or other quick-setting mortar is used for the backing to minimise the settlement of the joints.

## Arches

An arch is an arrangement of bricks, blocks of stone or other material for spanning an opening, and constructed in such a manner that the blocks mutually support one another, and divert the vertical pressure brought upon them by the load in an inclined direction to the supports at either side of the opening.

If carefully jointed with cement, and built of a hard material, arches over small openings practically act as lintels, and exert a vertical pressure upon their supports. Should a crack appear in an arch, however, after it has been built it will exert an outward thrust upon its supports. Arches over large openings always exert an outwardly inclined pressure upon their supports. For these reasons the supports should be made large enough to resist the maximum outward thrust that is ever likely to be brought upon them.

The following are the technical terms relating to arches: -

## Face

The exposed surfaces of an arch ring are called its faces.

## Voussoir

The blocks forming an arch ring are called voussoirs.

## Key

The central or uppermost voussoir is called the key or keystone.

## Springers

The lowest voussoirs of an arch ring are called the springers.

## Skewbacks

The bricks or stones cut to the necessary slope to receive the springers are called skewbacks.