Drawing a Staircase in Profile from Nature.

Imagine in the gallery you just depicted, there is a staircase placed to be viewed in profile. To draw it, you proceed as follows: find the width aB by comparing it to the total width AB. Then, focus on the first step, which consists of a geometric plane and two perspective planes, like the base of one of the columns or like the box in plate 3, figure 10. Determine the width a'b' by comparing it with the entire width aB, and similarly find the height a'e' by comparison with a'b'. You obtain a rectangle or geometrical plan a'b'c'd'. You could then proceed to complete this step as for the box in plate 3, figure 10, but it is simpler here to refer to the viewpoint. From points a, c, d, a', draw lines to the viewpoint after assessing how many times the width a'b' fits into a'e'. Here a'b' fits once and a half into a'e'. Therefore, take on the drawing and on the line here represented by a'e', a dimension equal to one and a half times a'b'. Thus you find the point e. Raise a vertical from this point to where it meets the line drawn from e to the viewpoint, with the meeting point being f, from which draw a horizontal line until it meets at g with the line drawn from a' to the viewpoint. Upon completing this step, extend the vertical raised from b' and give this vertical a height d' equal to b'd', representing the height of the second step, as all these steps are of the same height. In the rectangle a'b'c'd', draw the diagonal from d'a' which you extend indefinitely. Through points c and f, draw parallels to this diagonal; these two parallels will receive the profile of the staircase completed in this manner. From point k, draw a horizontal until it meets d'a' at m'; from this point m', raise a vertical that intersects c'd' at n'; from this final point n', draw another horizontal until it meets a'f, and so on. This method outlines every step you wish to draw. Next, from points represented by p,p',m,n,n',m', draw lines to the viewpoint or vanishing point of the first step. Then, from point q, raise a vertical until it meets the line drawn from r to the viewpoint, from k to e intersection point, draw a horizontal to the line from m to the viewpoint. From any interior point j, raise a vertical, etc. The inclination of the profile depends on the depth of the first step. The shorter the rectangle a'b'c'd', the straighter the diagonal a'c'. Conversely, the longer this rectangle, the more slanted the diagonal. In the latter case, the slope is gentler. In beautiful staircases, the top of the step should have a depth of one foot, and the step height should be five inches.