Timber is sawed in countries producing, or using it, in great quantities in saw-mills, in which the tools are worked by water or steam, as described in the last chapter; and it is also sawed into battens, laths, &c., by circular saws, turned by machinery, like a lathe; but when timber is sawed by hand, it is done by two men acting in concert in the following manner:--A pit is generally chosen, round the margin of which a stout frame is laid. The beam to be sawed is laid along the centre of this frame, in the direction of the length of the pit. One man stands on the beam while another is in the pit below him, and each alternately raises or pulls down a large vertical saw, with which the beam is cut lengthwise into planks. Wedges of wood are placed in the fissure as the work proceeds, to keep the cut open, and thus allow the saw to play freely. This is very hard labour, especially to the upper man, who has not only to raise the weight of the saw in the up-stroke, but to guide it correctly along the chalked line on the beam. This man gets higher wages, and is called the _top-sawyer_, a term technically given in jest to any one who is, or fancies himself, of superior importance. Scarfing or Joining Timber. When timber is wanted in lengths exceeding those that can be procured from the tree in one piece, it must be joined by what is called _scarfing_; that is, the ends of the two lengths that are to be united into one, are cut so that a portion of the one may lap over and fit into a portion of the other, which is cut so as to receive it. The timber, when united, is thus of the same uniform size. The joined ends are secured together by bolts or spikes. The following figures show the more usual modes of scarfing timber for different purposes. [Illustration] The last is a mode of scarfing invented by Mr. Roberts, of the Royal Dock Yards. Trussing or Strengthening.