FRAME, in gardening, the covering of any kind of hot-bed, Hued pit, or cold pit; used for the cultivation of plants not sufficiently hardy for the open air. Frames are of various materials, but generally of wood or iron and glass, and are made in one piece or in sashes according to the,size of the hot-bed or pit.
a bridge built of timbers framed together in such a manner as to obtain the greatest possible amount of strength with a given quantity of material.
The fundamental principle upon which all such construction is based, is that the timbers shall be so arranged that the weight put upon them shall exert a pulling or a_ crushing strain, instead of a transverse strain, and, if possible, that the greatest strain shall act as a direct pull in the direction of the fibers of the wood. The construction. of a frame-bridge is very similar to that of a roof, excepting that in the bridge a con siderable outward thrust upon the abutments is generally permissible, while the walls. of a house will not stand this; and that for the bridge a nearly level way on the top is desirable, while for a roof a steep incline is not objectionable, or is even desirable. In. a simple and useful form of frame-bridge, the weight upon the bridge will exert a. pulling strain upon a horizontal timber, and a crushing strain upon oblique timbers which extend from the extremities of the horizontal timber to the abutments, as well as upon the upper timbers; the main support is in the horizontal timber, which must. be torn asunder before the oblique timbers can be bent or displaced to any considerable extent, The celebrated frame-bridge of Schaffhausen, constructed in 1757 by Grubenmann, a village carpenter, was built exactly in the manner of a roof with a horizontal path way superadded. It was composed of two arches, one 193 ft., the other 172 ft. span. It was laid upon the piers, and did not abut against them to exert any outward. thrust. This weight on the bridge is transmitted by the oblique beams, which by analogy we may call rafters, to the tie-beam, where it exerts a horizontal pulling strain. These
rafters are framed into the tie-beam so as to abut firmly against it in the same manner as roof-rafters (see ROOF). This kind of frame-bridge is very common in Switzerland, where timber-bridges abound; and it has doubtless originated from the fact, that most. of the bridges have been built by the local carpenters, who are accustomed to the con struction of roofs- of considerable span for the- commodious .square-built wooded cot tages with overhanging roofs, so common in that country. Frame-bridges of more complex structure are sometimes built; in some of these, the timbers are framed so as to present an arched form. In these cases, the structure is very similar to those described under CENTERING. The serious defect of all such bridges is their liability to decay from exposure to moisture, etc., especially at the joints, where water is apt to lodge and remain, from want of free circulation of air to evaporate it. In the bridge of Schaff hausen above described, it was found that when it had stood but 26 years, the oak beams, where they rested on the masonry, were rotted, and the frames began to settle. This was remedied by a carpenter named Spengler, who raised the whole structure upon piles by means of screw-jacks, and replaced the decayed wood. Means should be adopted to admit the free circulation of air in those parts where the timber rests upon the masonry, and to prevent water from settling in the timber joints. The covered bridges of Lucerne and other parts of Switzerland are well known as objects of special interest to tourists, who usually imagine that the roofs are made for the comfort of trav elers, but their main object.is the preservation of the bridge.
. In the watch-trade, the man who frames all the parts together, and builds'up the watch, is called a finisher, and his work is called finishing, though it corresponds with what is called framing in other trades.