the whole, are a good looking lot, and it remains only to see that the walls are properly constructed.

Method to Be Avoided. In the first place the walls must be built entirely free from the bank so that they are self-supporting, Fig. 13, and give besides an opportunity of cementing the wall on the outside, as called for. This is a thing generally neglected, and yet it is far more important than that the inside of the wall should be smooth and handsome. The ordinary careless way of building the cellar wall of a country house, is to lay the wall up to the top of the ground without mortar, stones of varying thickness being brought to a face on the cellar side, with the "tails" of the stones in

Fig. 13. Good Cellar Wall

Fig. 14. Poor Cellar Wall

irregular projection on the outside, some partly resting against the bank and others barely filling out to the required thickness. The whole is finally smoothed over on the inside with a thin smearing of mortar, Fig. 14. This is a method which should be avoided for many reasons. In the first place, a wall of this kind is little or no protection against water, for the uneven projections on the external face serve to catch the water which runs down on the outside and to lead it into the inner face, where the thin pointing of mortar is very little protection. Then, too, any movement such as frost in the ground tends to overthrow the wall by reason of the long stones which tail into the ground, and often bear upon the soil in such a

way that any settlement or heaving of the soil will open cracks and cause the wall to bulge inward, as is often seen in country cellars. In reality it is more important to have the outside face of the wall smooth and impervious than the inside face. Satisfied that the stones which are being delivered are suitable for our wall, we shall need to give our attention mainly to the construction, to the mortar and bonding, to the solidity, and later to the pointing.

Mortar. The specifications require that all stonework below ground shall be laid in Portland cement mortar 1 to 3. This means 1 part of cement to 3 parts of sand, and makes a strong mortar. The portions which show above ground are to be laid in "half-cement" mortar, which we interpret to mean equal parts of cement and lime, and not half as much cement as lime, as some contractors will claim. This proportion of cement and lime with about 8 parts of sand will make a proper mixture; it should be thoroughly mixed as tested by the evenness of color and the smoothness.

For a wall particularly exposed to dampness, it would be well to use a stronger mortar than this, and to omit a large portion of the lime, only enough being retained to give a degree of smoothness to the mortar under the trowel. A proportion of 1 bag of Portland cement, 1 barrel of sand, pail of well-slaked lime putty will make a strong mixture, and one that works easily. A workman's mixture which closely corresponds is measured by the shovelful: viz, 10 "shovels" of cement, 30 "shovels" of sand, and 1 "shovel" of lime.

Lime. In slaking the lime for mortar it is important that the water, in the proportion of 11⁄2 barrels to 1 barrel of lime, should be added in as large quantities as is practicable, since putting the water in by bucketfuls and stopping to stir the mixture each time, tends to chill the lime which is already beginning to heat. After slaking, the lime must stand as long as possible before being mixed with sand, and the cement should not be added until the mortar is needed, since it will set in a few hours. To be of good quality, the lime should be free from cinders and clinkers; it should be in hard lumps and have little dust. It ought to slake actively and entirely, making a fine soft paste with no residue or "core". Lime should always be slaked in a pen built of boards, never on the ground or in a hollow in the sand. A pen about 4 feet by 7, and 10 inches deep, is large enough to mix a cask at a time.

Some kinds of lime when slaked leave a residue of stones and gravel, and when this is the case, instead of having the mortar made in the same box in which the lime was slaked, the mixture is thinned with water and is run through a fine sieve into another box. If Rockland lime is used, as is specified in our case, this operation will not be necessary.

Sand. The sand used should be sharp and free from dirt, loam, or other impurities. To obtain this, it is generally necessary to screen the sand. For our purpose a rather coarse sand will make the strongest mortar. It must be carefully inspected and in case of any doubt should be tested for purity. One test consists in putting a handful into a dish of water; any dirt or impurities will at once rise to the top as the sand sinks. Another test is to squeeze a handful of wet sand; if upon opening the hand, the sand retains its shape and soils the hand, it probably contains loam or clay and should be rejected; if it falls down loosely without staining, it is probably clean and good. The presence of fine loam in the sand will make the mortar work more easily and for that reason it is sometimes used by unscrupulous builders.

Cement. There are many brands of Portland cement, the kind called for by the specifications, and they are so well known that for ordinary purposes it is only necessary to see that the casks bear the name of the specified brand, and that the cement is fresh and has not become crusty from absorbing moisture. In case of doubt, simple tests of the setting quality and soundness may be made by the superintendent. For the initial set a small amount of clear cement may be mixed with water enough to make a stiff mortar, and the time noted which is required for it to set hard enough to support without indentation a wire inch in diameter under pressure of a 1-pound weight. Good cement should not harden to this extent in less than 30 minutes.

To test for soundness, mix some cement with a little water in several pats about inch thick and 3 inches in diameter, running to a thin edge. After these pats have been kept under a damp cloth for about 24 hours, place some under water and leave some exposed to the air for a few days. If the cement dries in the air with a light color and free from cracks, and sets under water with a darker color and free from cracks, it may be considered of good quality; but

if any one of the cakes cracks or becomes twisted and bubbly, it shows a quality of cement which is inferior and should be rejected. Cement must be kept in a dry place, for a little moisture will cause it to set and it will soon become worthless.

Construction of Wall. Upon our next visit, we find that the trenches all around the cellar have been filled and a portion of the wall laid, starting from the corner and running some ten feet in both directions. 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, 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 stipulates a bond stone in every 10 square feet of

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Fig. 15. Rubble Wall Leveled Off

wall, and we carefully examine the wall already built to see if this has been done. In a wall such as we require, that is, one with practically two faces, there is often a tendency to build the two faces with long narrow stones and to 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 lack of bonding. To detect this defect in a wall already built, but before the mortar has set, a very useful instrument is a steel rod about inch in diameter and 4 feet long. Thrust down into the center of the wall, this will show at once whether the stones are laid to overlap each other or not, and also whether the stones in the center are well bedded or not, as they will rock and jar when struck with the rod if not thoroughly bedded. No stone should be set with a depth from the face of less than 6

inches, and all stones should be laid so that their split surface is horizontal, breaking joints in the length of the wall, as well as through and through, and all angles should be bonded alternately,

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

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, for in rolling the stones up to their places on