The first thing in commencing to build a stairs is to make the pitc/i-board; this is done in the following manner: Obtain very accurately, in feet and inches, the rise, or perpendicular height, of the story in which the stairs are to be placed. This must be taken from the top of the lower floor to the top of the upper floor. Then, to obtain the number of rises and treads and their size, proceed as directed in Art. 252. Having obtained these, the pitch-board may be made in the following manner: Upon a piece of well-seasoned board about 5/8 of an inch thick, having one edge jointed straight and square, lay the corner of a steel square, as shown at Fig. 127. Make a b equal to the riser, and b c equal to the tread; mark along the edges with a knife, and cut by the marks, making the edges of the pitch - board perfectly square. The grain of the wood should run in the direction indicated in the figure, because, in case of shrinkage, the rise and the tread will be equally affected by it. When a pitch-board is first made, the dimensions of the riser and tread should be preserved in figures, in order that, in case of shrinkage or damage otherwise, a second may be made.