During the time of lifting, the workmen were arranged in pairs opposite each other, and on each side of the wall, where each one had 12 to 14 screws to maneuver. In order to render the motion very uniform, the superintendent of the work gave signals by means of a whistle. At this moment each man gave the screw a half revolution, passed to the following one, and continued thus until all the screws under his supervision had been revolved to the same degree. At a fresh signal this operation was begun again, and so on.
When the building had been lifted to a height of twelve inches, it became necessary to raise the screws. To effect this, two rows of beams (Fig. 7) were added to the timber-work, and each screw was moved in succession, so as to always leave one in position. By these means the building was gradually lifted to the desired height, and it now became necessary to take the requisite measures for moving it back. With this object in view, spruce floor timbers, e, very smooth and well lubricated with tallow and soap, were laid upon the timber work and afterward covered with oak planks, d, one inch in thickness, and upon these latter were placed joists, c, that supported string-pieces, b, that were firmly fixed to the joists by means of spruce pins driven in with force. As the floor timbers that were employed had to be as long as possible, they were united end to end by a strong joint and prolonged as far as the new spot upon which the edifice was to rest. Throughout their whole extent they were supported by sleepers that were fixed firmly in the earth. The entire weight of the structure being carried by the pieces, a, b, c, d, e, and f, after the removal of the screws, the jacks, V, were then placed in position, their heads resting against the string-pieces, b, at the points marked S, and their other extremities being received by a framework set into the earth. It took but twelve jacks to move the entire mass, and these were maneuvered under the orders of a superintendent, who transmitted his signals with a whistle.
It took forty days to perform all these operations, and it required fifty men to lift the structure. After the jacks, V, had been put in place, the building was moved in three days, or at the rate of 11.68 feet per day. This is a medium rate of speed to be adopted in the moving of a structure like this, for, under very favorable conditions, it might be carried to over eighteen feet per day.
The timber work which was used in lifting the building was afterward put together again, in the same manner, around prolonged foundations, and the same were put in place a second time after the manner described above. After the floor timbers, e, had been removed by slightly lifting the load, and the structure had been lowered to its proper position, the intervals between the cross-pieces, a, and the walls of the new foundations were filled in with masonry; the mass was then allowed to settle gently down into its place and the cross-pieces were removed.
When buildings stand very near each other, timber-work cannot be put together outside of the walls, and it therefore becomes necessary to adopt the arrangement shown in Fig. 9, all the work being done here beneath the structure. The cross-pieces, a, occupy here the entire width of the house, and are spaced about 36 inches apart from axis to axis. The structure rests upon two pieces of timber work constructed like the ones mentioned above. Besides this, it is necessary to utilize the timbers, L, of the flooring, P, for supporting a part of the load.
During the widening of State Street, in Chicago, several three or four story brick structures were moved in this way. One of these houses was set back about four feet without the necessity of lifting it. Apertures (Fig. 10) four feet in length were cut in the foundation walls, the edges were made level, and planks, c and c', were inserted and fixed in tightly by wedges. The intervening masonry was removed, and, after laying planks alongside of those already in place, the structure was put in motion in the ordinary way.
When single threaded screws are employed for moving buildings, it requires much time and manual labor to place and move the pieces. For the purpose of securing greater rapidity in these operations, Mr. Hollingsworth has devised a sort of jack-screw (Fig. 11) that consists of a steel screw about eight feet in length and three inches in diameter, provided with two threads, running in opposite directions. The nuts are set into the corresponding extremities of two beams, one of which abuts against a cast iron brace-block, n, held in place by a stirrup-iron, t, while the other bears against the string-pieces, b. Thanks to this arrangement, a structure may be moved at one time over a length of 6 feet instead of 1.3, the latter being the maximum travel with single screws.
The method in which slide beams, f, are prolonged in view of resisting the pressure of the jacks is scarcely employed at present, the objection to it being that it occasions changes of direction from the line formed by the timber work. For this reason, contractors prefer to use independent posts to receive the jacks.—Revue Industrielle.
FILTER FOR INDUSTRIAL WORKS