Dampness in walls may be prevented, and a more uniform temperature secured in the rooms, by enclosing a stratum of air in the wall. A space of about three inches, should be left between the outside half brick, or stretcher, and the inner wall: this space may be commenced on the foundation course; where it is desirable to have the basement story dry ; where it is not, it should be commenced at the first floor, and extend around the building. Then cut wire about three-sixteenths of an inch in diameter (or not thicker than the joints in the wall are intended to be) into pieces, nine inches long, bend one inch of each end of these pieces to a right angle, and both ones In the same plane, roi Uoo to connect the wall across this space. Every three courses lay them over it, about two feet apart, with their ends half away across the bricks upon which they lay, so as to have them not over each other, but equally distributed along the space. If the space is not over three inches wide, it may be closed at the top by a heading course, which, being sheltered from driving rains, by the cornice, and eaves, will not conduct any water to the inner wall. At the ends of the building it may extend to the top of the joists, and the wall be dropped off the thickness of the space, and then built solid, or it may be continued to the rafters. At the door and window jambs the band may be kept as usual, by clipping the headers; and at the chimney, the space may be stopped at the flues, and greater thickness of the chimneys will insulate them. As atmospheric air is one ol the very Worst conductors of heat, it will prevent the wall from being suddenly heated or chilled through by changes in the weather. In very cold climates it would be better to have strips of sheet iron, three and a half inches wide, laid along over the space at the top of each story, with one edge resting in the joint of the outer wall, or upon the wires, and the other leaning back against the inner wall, so as to be highest on the inside, and the partition walls to extend across the space and connect with the outer wall. This, by cutting off the communication, would prevent the air, as it acquired a more elevated temperature by the heat of the room in which the fire is kept, from rising, and its place being supplied by tha colder air from other parts of the building ; and then, by having duplicate sash in the windows, with a stratum of air between them, the insulation would be complete. To prevent injury to the wall, Jrom the expansion of the enclosed air, small openings should be left between the ends of the bricks, near the bottom of the space, about half an inch wide, or not large enough to admit rats. The pieces of wire may be dipped in pitch or oil paint to keep them from rusting. These pieces of wire may appear to be a slender tie to many, but it should be remembered, that though a single hair is quite slender, a horse may be pulled out f the mire by his mane, and any required strength may be attained by increasing the number of wires. But placed as above recommended, the wires would bind the wall better than it is often done by the present mode of binding it without heading bricks, for as the tie is hidden by the first course that is laid over it, it is liable to be forgotten and neglected; and this may be one cause of the frequent falling of walls in your great city; the wires across the space will, at any time, be visible, until the space is closed. For this imperfect mode of binding the outside wall, it would be better to leave the space nearest to the inside wall, as the thin part would then be less exposed. By superseding the old Flemish or English bond, with the present modes in common use, the gain in beauty is not commensurate with the loss in strength, and mechanics generally are too much inclined to sacrifice the latter to the former. Those, however, who acquire a character for doing the most substantial durable work, should have the preference; they at least have the pleasure which arises from the consciousness of having done their duty. By having bricks of double width moulded, and every filth or sixth course laid with them, the bond of all stretchers might be preserved, without at all diminishing the strength of the wall; but so far as my observation has extended this has not been done. HEZH. POLLARD. Lafayette, Mo. Aug. 8, 1853.