the crandall is used from one side or from both. If a smooth finish is desired the stones may be rubbed. This is easily and cheaply done when the stone is first sawed, and makes a good finish. Vermiculated work, shown in Fig. 162, is obtained by working the whole surface over in imitation of the destruction by worms. This is expensive and is rarely used except for quoins.

Supervision. The inspection of stone at the building should be very thorough, especially in the matter of finish. The finer the degree of finish the more costly is the labor, and for this reason there is often a tendency to slight the work. Eight-cut granite will often be found to be six-cut, and fine pointed or fine crandalled work will sometimes be found to be rough and coarse.

STONE MASONRY

Rubble. Of the different kinds of stonework, rubble masonry requires the least preparation of the material. It is used for many sorts of construction, from ordi

nary foundation walls, such as we have already considered, to the handsome well-pointed masonry of churches and other buildings.

Fig. 163. Uncoursed Rubble

Types. Two definite classes of rubble work are recognized: (1) uncoursed rubble, in which stones of irregular shape are laid as they come to hand with no attempt at level courses, Fig. 163; and (2) coursed rubble, in which the blocks are leveled off at regular heights to a horizontal bed, Fig. 164. A wall of rubble is finished by pointing up the joints with cement mortar, colored as preferred, but usually matching the stone when that is at all even toned. Sometimes a false joint of red or white mortar is run upon this pointing to imitate ashlar work.

Uncoursed rubble in some cases is laid with the pieces having hammered joints which are fitted together with no spalls, or small stones, between, Fig. 165. This is an expensive and tedious process but is very effective when well done. The coursing of

rubble is not necessarily uniform, or at the same level throughout, but may rise and fall by level stages to accommodate the size of the materials.

Laying Stone. The superintendence of this class of work, beyond a general inspection of the quality and soundness of the

Fig. 164. Coursed Rubble

Fig. 165. Hammered Joints with no "Spalls"

stone, involves mainly seeing that the stones are well laid after they have been suitably prepared by roughly squaring them with a hammer, and knocking off all weak angles and projections. The

Fig. 166. Stone Wall Facing with Iron Ties

stones should be clean and free from dust, and should be moistened before being laid. Mortar must be used in sufficient quantities to permit each stone to be firmly placed, and all hollows between the large stones should be filled with small stones carefully bedded in the mortar. The large stones should be laid on their natural bed, and should be so used that the side parallel to the bed will be the largest, so that the stones will lie flat and in no case be set on edge or on end. Care must be taken to break joints, and no side joint should form an angle with the bed of less than 60 degrees.

Bonding Stone. The bonding of a rubble wall must be carefully watched. Bond stones must be freely used. If the rubble is backed with brick, as is often the case, iron clamps and ties should be inserted, which may run through the wall and turn up behind the brick if the back of the wall is to be concealed, and which should run to the inside

course of bricks in any case, Fig. 166. If rubble is used as a backing for cut stone, the facing should contain a large proportion of thick stones which will bond well with the rubble. These bond stones may be left rough at the back and sides, but the upper and lower beds should be level, so that the stones will have no tendency to wedge off the backing. The backing should be carried up at the same time as the facework, with the coursing leveled off at the same place. A good proportion of thick stones running two-thirds or more across the thickness of the wall is better than a few extending through the wall.

Fig. 167. Ashlar Masonry

Ashlar. Ashlar masonry consists of blocks of stone which have been cut to a regular figure, generally rectangular in shape, and laid in courses usually a foot or more in height, Fig. 167. If the courses are not maintained at the same level continuously, but are laid of stones of unequal height which are, however, still level and plumb, the work is called

broken ashlar, Fig. 168.

In all ashlar work with soft material, such as limestone, no stone should have a length greater than three times its height. In harder stone the length may be four or five times the height. The thickness in soft stone may be once and onehalf or twice the height; in hard stone, three times the height.

Fig. 168. Broken Ashlar Masonry

Laying Stone. The bed upon which the stones are laid should be level, cleared of dust or refuse, and well moistened with water. Upon this the mortar is spread evenly. Wooden wedges of the thickness of the joint are then laid on the face of the bed, and the stone carefully lowered upon them, to be moved into exact position

by the aid of a pinch bar. In using a bar or rollers to handle cut stone, it will be necessary to protect the edges of the stone by bagging or other "softening". When the stone is in its final position, the wedges may be removed and the stone settled into place and leveled by striking with a wooden mallet. In the case of heavy stones, where there would be danger of the weight of the stone squeezing the mortar out of the joint, the wooden wedges are allowed to remain until the mortar has set.

of Hollow and

Slack Joints

The bed of mortar should be kept back an inch or so from the face of the stone, so that the stone will not bear on its outer edge. This will save raking out the mortar when the wall is to be Fig. 169. Bad Effects pointed, and will prevent any danger of the splitting-off of spalls on the face, which might occur on account of the mortar on the face of the joint becoming hard sooner than the inside, and the unequal settlement bringing pressure on the edge of the stone. The same mishap may occur if the bed of the stone is cut hollow or slack, as in Fig. 169, when the settlement of the mortar will bring the whole pressure upon the front edge of the stone. For this reason, care should be taken that the bed joints are square and true.

Door and window sills should be bedded only under their ends, as the natural settlement would cause them to break if bedded

under the opening, Fig. 170. Stone work in damp situations should be set in cement mortar, but lime may be used if the situation is dry. Limestone and marble, and some sandstones, are often badly stained by the use of cement mortar, and inquiry in respect to this should always be made before using an unfamiliar stone. In case of danger of staining, Lafarge cement, made of lime, plaster of Paris, and marble dust, may be used; it should be plastered over the back of the stone as well, if cement must be used in the backing.

Fig. 170. Proper Bedding for Window Sill

Bonding Stone. Care must be taken that no vertical joint in

any course comes over a joint in the course below; the stones should break joints or overlap, preferably to an extent of from once to once and a half the height of the course, so that each stone will be supported by at least two stones of the course below, and will in its turn support at least two stones of the course above. This will not only distribute the pressure of the weight above, but will tie the wall together in its length by means of the friction of the stones where they overlap. The thickness of the stones should also vary so as to make a bond in and out of the wall, Fig. 171, and at least one stone in every ten square feet of wall should be the full thickness of the wall. The strongest bond in a wall of cut ashlar is one in which each course contains a header and stretcher alternately, the outer end of each header coming at the middle of the stretcher above and below, Fig. 172.

In broken ashlar work, the bond should be carefully preserved, and if there is a brick backing it will be convenient to use stones of a thickness of 4, 8, and 12 inches, alternating so that the bond may be obtained through and through without much cutting of the bricks. As the joints of the brick backing will necessarily be more numerous than the joints of the ashlar facing, the former should be made as thin as possible, and cement should be used to prevent their shrinkage. The backing should not be

less than 8 inches thick. If the L

facing is in courses exceeding a

foot in height, each large piece should be tied to the brick by iron clamps, placed about every three feet in the length of the wall and every two feet in the height. It will be of advantage in this class of work if the horizontal joints are not allowed to run to a great length. Changing the level of the courses every four or five feet will make a good looking wall. Broken ashlar is usually prepared at the building site, but it is a saving if the stones are cut to the required heights in the yard, only the end joints being cut at the building.

Fig. 172. Bonded Ashlar Masonry