This section is from the book "Cyclopedia Of Architecture, Carpentry, And Building", by James C. et al. Also available from Amazon: Cyclopedia Of Architecture, Carpentry And Building.
Upon our next visit, we find that the trenches all around the cellar have been filled and a portion of wall laid starting from the corner and running some ten feet in either direction. Our first care is to examine the lines by which the work is being laid up. We note that each line is tied to its proper notch on the batter boards and that the men are working to plumb lines hanging at intervals from the long lines (See Fig.7), using the stones about as they come to hand, the only preparation being to square the too irregular ones, to make a face on them by the use of the stone hammer. We caution the mason to level off the wall about every two feet (Fig. 15) and to keep the horizontal joints as near to a level as possible. We also call his attention to the clause in the specifications which calls for a bond stone in every ten square feet of wall, and carefully examine the wall already built to see if this has been done. In a wall such as we require, that is, with practically two faces, there is often a tendency to build the two faces with long narrow stones and fill in between with small stones which are put in nearly dry with a little mortar on top to show well. Such a wall has an appearance of strength on the faces, but under a heavy load may fail from lacking of bonding. To detect this defect in a wall already built, and before the mortar has set, a very useful instrument is a steel rod about 3/16 inch in diameter and four feet long. This will show at once, by being thrust down into the center of the wall, whether the stones are laid to overlap each other or not, and also if the stones in the center are well bedded or not, as they will rock and jar when struck with the rod if not bedded thoroughly. No stone should be set with a depth from the face of less than six inches, and all stones should be laid so that their split surface is horizontal and breaking joints in the length of the wall, as well as through and through, and all angles should be bonded alternately, using the largest stones for the corners. (Fig. 16.)
Fig. 15. Rubble Wall Levelled Off.
Fig. 16. Corner of Wall.
The corner which has been built, we find to be well bonded, as the first corner of any wall is apt to be when stones are plenty and near at hand (it is the last corner of a cellar wall which will need the sharpest watching), but about six feet from the corner we discover a line of vertical joints which runs irregularly but continuously, through four or five courses. (A, Fig. 17.) We call the man who is working upon this part of the wall, and point out the defect to him with instructions to take down the wall until he can bond over the second course, and we caution the foreman to watch sharply against this sort of construction. Another bad practice which some masons encourage, is that of filling the spaces between the larger stones with chips or pebbles, put in dry, and then smeared over with mortar which is more or less carefully worked into the seams. This kind of work will be easily detected by use of the steel rod, which we can feel moving the stones if poorly bedded. The right way is to settle each stone, no matter how small, into a bed of mortar either by rubbing with the fingers or by tapping with the trowel or hammer. In heavy work all large stones should be set with a derrick, as in rolling the stones up to their places on planks set up against the freshly laid wall, there is not only danger of shoving the wall out of plumb, but the bed of chips and mortar which has been prepared is sure to be torn up, and there is no certainty that the stones are properly bedded. Satisfied with the work which has been done so far, we give orders that the filling in against walls be done with coarse gravel or broken stone well puddled with water or settled by ramming.
Fig. 17. Straight Joint in Wall.