outside of the building where it was placed and 30 or 40 feet away from the foundation pier, and we were in a fix. We did not have time to take it up, and would not have known what to do if we had taken it up; but as an experiment I excavated a trench which was an extension of the foundation of the engine, lengthwise, for a distance of about 60 feet, and I filled that trench with firm material and rammed it down. I filled in about half of it first, and we started the engine. We found the vibration nearly ceased. Then I extended it about 30 feet farther and rammed that trench full, and we killed the vibration, and since that I have adopted the old farmer's method of digging a post hole and setting a post, by filling it with material and ramming it down, and I have found that answers as well as stone in a great many cases.

BÉTON IN COMBINATION WITH IRON AS A BUILDING MATERIAL.

BY

W. E. WARD, PORT CHESTER, N. Y.

IF society is indebted to the restless spirit of progress for most of its modern comforts and conveniences, it certainly is not yet a debtor for any methods which guarantee immunity against calamities from fire. While other departments of industry have received the benefits of improvement, the continuous and persistent use of combustible material for exposed portions of buildings has limited the intrinsic elements of the art of building construction, and confined improvements only to matters of design.

Incombustible materials are easily obtained and much better adapted to the purpose for every apparent reason. Doubtless the question of increased cost, both in money and in time, required for more thorough construction may be in a measure responsible for the tardiness in adopting safer methods, and, in addition to greater expenditure, there may have been a want of confidence in the fire-proof methods which have been offered to the public for adoption. The importance of this question induced the writer, in 1871 and 1872, to make some experiments in a new and special direction, for the purpose of ascertaining whether a practically fire-proof building could be designed and constructed at a comparatively moderate cost.

The incident which led the writer to the invention of iron with béton occurred in England in 1867, when his attention was called to the difficulties of some laborers on a quay trying to remove cement from their tools. The adhesion of the cement to the iron was so firm that the cleavage generally appeared in the cement rather than between the cement and the iron.

The line of experiments which followed were confined exclusively to working up the reciprocal value of béton, in combination with iron, in the construction of beams which were designed for supporting floors and roofs made of the same material. In this particular, the facts were conclusively developed, beyond question, that the utility of both iron and béton could be greatly increased

for building purposes, through a properly adjusted combination of their special physical qualities, and very much greater efficiency be reached through their combination than could possibly be realized by the exclusive use of either material separately, in the same or in equal quantity.

Experience had long ago proved that unprotected iron, associated with combustible materials, is altogether unreliable for building purposes when exposed to a severe fire test; but it has been demonstrated that if iron is well protected by a heavy clothing of béton, its integrity can be safely depended upon under almost any emergency.

When all doubts were removed concerning the reliability of the several combinations of materials required in the construction, a building embracing the following radical new features was erected, for dwelling purposes, near Port Chester, N. Y. Not only the external and internal walls, cornices and towers of the building were constructed of béton, but all of the beams, floors and roofs were exclusively made of béton, re-enforced with light iron beams and rods.

Furthermore, all the closets, stairs, balconies and porticoes, with their supporting columns, were molded from the same material. The only wood in the whole structure was in window-sashes and doors with their frames, mop-boards and the stair-rails; thus excluding everything of a combustible nature from the main con

struction.

Béton can be used in any form of construction, and is able to serve the requirements of any architectural or decorative effects. All the exterior portions of this house, which are more or less ornamental in their functions, were made of béton in place during the progress of the work. In the interior of the house, the cornices, stiles, and panels of the ceiling are formed of béton, and covered with the hard finish usual in such work. There appears to be no limit to the reproduction in béton of any form used in stone masonry or in stucco. The proportions of material composing the béton for the work varied in strength to meet the requirements of the different parts of the structure, the heavy walls needing the least proportion of cement, while the beams, floors and roofs required a much larger proportion. Only the best quality of Portland cement, clean beach sand, and crushed bluestone were used in combination with iron for constructing the building.

The proportions of cement used for the heavy wall work were one part of cement to four parts of sand and fine gravel, thoroughly mixed dry, and dampened with only sufficient water to give it the consistency of well-tempered molding sand.

A finely crushed and screened hard blue limestone was found

to be better adapted for use in combination with the béton than a coarse-sized stone filling, because small-sized stones pack closer than large ones, thereby realizing a proportional saving in cement. The tests made to ascertain the comparative transverse strength of different compositions proved that the bond was stronger in béton made with small stone. In breaking test-sections made of béton in the form of bricks, the fracture of those filled with small stone

was almost invariably across the stone lying in the line of fracture, while the fracture of the test bricks made with a filling of stone three or four times larger, showed a frequent tearing away from the bond between the béton and the larger stone filling, the composition of the béton being the same in both cases.

The proportions of cement and coarse beach sand and gravel, used in re-enforcing iron beams for floors and roof supports, were one part of cement to two parts of sand and gravel. The size of the iron beam, selected for an experimental test, was a four-inch I beam of lightest pattern, twelve feet long, weighing thirty pounds to the yard, and its safety load was limited to eleven hundred and fifty pounds. A plank mold was made the length of the iron beam, twelve inches deep by five inches wide, in the bottom of which a layer of béton was first moderately tamped down to an inch in thickness; then the iron beam was laid on the course at equal distances from each side of the mold, and settled down on the surface of the course of béton to a good bearing. This brought the top surface of the beam seven inches below the top of the mold. The work of filling and tamping the courses was then continued until the mold was filled.

The reason for placing the iron beam so near the bottom of the mold was to utilize its tensile quality for resisting the strain below the neutral axis when this composite beam was exposed to heavy loads, while the béton above this line was relied on for resist ing compression from load strain. The béton became thoroughly hardened in about thirty days, when the following tests of transverse strength were made. It was placed upon suitable supports, with a bearing of three inches at each end. A lever was adjusted so as to bring the testing load on a knife-edge bearing at the centre of the beam. Weight was then applied to the long end of the lever, until the stress on the centre of the beam reached nine thousand five hundred pounds. Under this load there was a deflection at the centre of the beam of seven-sixteenths of an inch, but not a sign of rupture appeared at any point.

The load was then removed, and the beam returned to the original line it occupied before the test, showing that the combination possesses the essential quality of elasticity in addition to the enormous increase of capacity to resist strain over that which was possible for either material to sustain if used separately and in the same quantity.

It is suggested for future construction that an inverted