CONSTRUCTION IN WOOD.
This branch of the work will be devoted to the construction of build ings intended for the more common uses, in which the chief material is wood in the form of beams, boards, laths, etc. Timber is reduced to the form of the beam either by hewing- or sawing from the tree-trtink, while the other forms, such as planks, boards, battens, etc., are always made by cutting- them with the saw from tree-trunks of certain fixed leng,ths. Spruce, pine, and hemlock are the woods most frequently used in building-, but considerable diversity in the practice of the different sections grows out of the relative scarcity or abundance of various descriptions of trees.
lUonclen Structures possess great significance in the United States, as the pioneer settlements of nearly all sections consisted chiefly of log cabins or weatherboarded houses; and a large proportion of the existing dwellings that are not located in large cities are made chiefly of wood, because it is the cheapest and most abundant material, and even in many districts where lumber must be obtained from comparatively distant points it is still cheaper than stone or brick. The notable changes to the more substantial and less inflammable materials have occurred chiefly in towns and cities where extensive conflagrations have led either to the legal prohibition of new wooden structures or to their prohibition by the voluntary action of many persons.
Portabie Il'ooden manufacture of portable houses of wood which may be transported in sections, with each part so marked as to designate its place in the finished structure, has become an important in dustry in the United States. At the present time portable buildings are made in great variety of size and style, many of them being designed with the view of permanent occupation, and the perfection with which all the needful details relating to their manufacture and the assemblage and erec tion of their parts has been worked out is specially interesting. The field 'for such portable buildings is very large. There is a constant demand for them from engineers of public works, railroads, canals, etc., especially in regions remote from settlements; they are particularly adapted to the needs of the military service in time of war, when portable barracks, hospitals, etc., are especially in demand; they are also well adapted for the needs of
contractors, miners, sportsmen, photographers, cainping-out parties, bath ing-liouses, pavilions, frnit-stands, summer-kitchens, and outbuildings of every description. As above stated, the manufacture embraces not only buildings intended for temporary use, but also more permanent structures haying considerable pretension to architectural effect. These larger houses —one, two, or more stories in height—are adapted for smnmer cottages, and may be obtained of many styles and as elaborately finished outside and inside as may be wished. Other styles of these portable structures are intended for railway-stations, depots, storehouses, etc., and may be had of any desired dimensions.
Timber Connections. —The means used for joininp.-, woodwork differ en tirely from those employed in stone construction. These means consist rrincipally of iron clamps, bolts, screws, spikes and nails, and wooden pins or treenails; otherwise, wherever wood is employed in the form of beams or posts in the regular framework, the sepamte timbers are chiefly brought into close connection by the insertion of the one into the other to a greater or less degree where they come in contact.
Saufing.—In their different connections the timbers may meet in the direction of their leng,th or at an angle, or they may cross one another. Figure (fi/. 3) gives an example of a joint of the first kind, the so-called " oblique scarfing " with notch and wedge. This joint is so arranged that after driving- the wedge between the small indents the parts cannot be separated in any direction. In other respects the Figure is self-explanatory. Figures 2 and 3 (pi. 3) exhibit square halving, applicable where two tim bers cross at a right angle (fig. 2) or at an acute angle (fig. 3) and are to lie flush with each other and not project. It need only be added in refer ence to Figure 3 that, to prevent turning, this form of scarfing is provided on the upper surface with small triangular notches at each side.