Very good standards for fences may be made by cutting half mortices in the opposite sides of a squared log, 4ft. or 5ft. long, as in Fig. 6, then cutting it into planks, and, before these are quite detached, sawing it down in the direction of the diagonal line; a pair of these are matched together, as in Fig. 7, and the lower end morticed into a flat plank so far as to let one hole come below it to receive a key to fix it there. The horizontal plank should rest upon a short log at each end, and it may be held in place by a couple of notched pegs driven into the ground.
Walls, to build.
Many of the natives of South Africa are very handy at building rough stone walls; but they require an overseer to insure the proper binding of the stones as they are laid. Some of their own countrymen may be found with skill enough for this. It is no use to build up two fair faces, as in Fig. 8, and then fill up the middle with loose stones—their weight would be sure to force out the sides and bring down the whole structure; but large flat stones should be chosen, as in Fig. 9, to reach either quite through the wall, or at least so far that the stones on the other side may meet and have a bond with them. Such walls, miles in length, are built without cement of any kind. If galvanised iron wire is to be used for fencing, to support upright rails, it is a good plan to have two rail-heads fixed at the proper distance, and to make the turns of the wire on these to insure each loop being equidistant, as in Fig. 10.
Chalk lines and measuring lines of all kinds suffer from being coiled or rolled up by hand—turns and kinks are put on or taken out of them; and it is much better to have reels, either like the log-reel of a ship, or like Fig. 11 (see [p. 290]), where a peg in the circumference of the disc serves as the crank by which to wind it up.
Plank screens to make.
Effective screens can be readily extemporised with planks of any kind and ropes; the simplest plan is to double the rope, making one part somewhat longer than the breadth of all the planks to be used, and leaving whatever spare end may be upon the other to hoist the screen by when finished. The first plank is laid in the bight of the rope, the two parts of which are then crossed and the next plank laid between them; they are crossed again for the third plank, and so on till all are inclosed. If there is not an eye on the shorter end of the rope, make a bow-line knot or two half hitches on it (see “[Knots and Hitches]”), and pass the longer end through; then lead the spare line at each end of your screen over the forks of trees, or sheer legs, or whatever support you mean to use, and hoist away simultaneously and carefully; for this arrangement, though perfectly strong and secure while every part remains in its proper place, is most easily disarranged; and in fact the great advantage of it is that, when no longer required, it can be shaken to pieces like a house of cards, leaving neither holes or imperfections in the planks nor kinks or knots in the rope. We have shown the boards rather far apart in our illustration for the sake of distinctness, they will lie closer, but they must always be separate by more than the thickness of the rope. They may be made to lie closer by omitting to cross the ropes and “stopping” them together with small cord, as in Fig. 2; or a perfectly weather-proof wall with overlapping edges may be obtained by looping the rope into a chain, as in Fig. 3, taking care to make the lower link well fast, for on this the security of the whole depends. To take this to pieces nothing more is necessary than to slip each loop off the end of the plank; let go the fastening of the lower end, and all the links of the rope chain will shake out.
Great firmness may be imparted to any of these arrangements by placing a small pole inside, and securing every plank to it by successive hitches of a smaller line, as in Fig. 4; or, if stouter poles be used, the walls may be built up in this manner, commencing from the bottom plank and fastening the upper ones as you go on. Each plan will have its advantages under peculiar circumstances. In the Indian islands, large hollow bamboos are either split into three or four parts, making somewhat rounded narrow planks, or an incision is made in the side of the cane, when it is opened out, laid flat, pressed, and converted into a single plank. Movable screens of considerable size are made in the same manner as in Figs. 1 and 2 already referred to.