1783. The borning-piece (fig. 426.) is composed of the body (a), commonly a thin slip of board, four inches wide, half an inch thick, and four feet two inches long; the head (b) of a similar slip of board placed across, but only eighteen inches long; and the foot is either of the same form as the head, or merely the squared end of the body (as in the figure). The upper and under edge of the head and foot must be perfectly straight, and form right angles with the edges of the body. Borning-pieces are used to prove, complete, and continue level lines, or lines on certain given slopes. One is placed at each end of a convenient length of the level or slope, and there held perpendicular to its surface, and, others being placed in the interval, and in the same line or vertical plane, the ground under the feet of the intermediate borning-pieces is raised or lowered till it is brought to the proper level or slope, when the upper edges of all the heads will range. Where box-edgings are to be planted with accuracy and beauty, the use of these implements cannot be dispensed with.