Fig. 2. Make R S equal stretch-out of the quadrant, Fig. 1. Set up one tread and riser above and below, as they occur on the centre line of rail, Fig. 1. For development of tangents make C 2 1 equal A B C, Fig. 1. Square out a level line from the springing at S to cut the line 1 at A. Join A C for tangents, which will be the same pitch as the straight rail.
Fig. 3 shows face mould. Make C B S equal C B A and B C equal B C, Fig. 2, and S C equal the diagonal of the square on plan. Draw C O and B O parallel to A B and B C. Draw sine major axis and sine minor through O. Notice the major axis is parallel to the diagonal from A to C, and the minor axis is the other diagonal. Both pitches being the same throws the horizontal trace parallel to the diagonal from the centre to B. One bevel will do for both shanks, as the pitches are the same. The falling line will be in the centre of plank at both ends and at the minor axis.
Fig. 4 shows the section, which is the same for both ends, only of course the reverse hand.
Fig. 6 shows the plan of centre line of rail of a side wreath starting from a newel. Lay down the tangents A B and B C equal in length and to the required angle, according to circumstances, the size of the hall, &c. The farther it stands out into the hall the better it will look, but it must not obstruct the passage or be out of proportion to the size of the stairs. B should be in front of the second riser, or it will make the rail too high at the newel. A will be the face of the newel. Draw from A square to A B, and from C square to C B to meet in O. Then O A will be the radius of the centre line of rail, which draw. Then A B being level will be the horizontal trace.
Fig. 7 shows the elevation. Set up a tread and risers and draw the springing C as it occurs on the plan. Make C 3 equal C B, Fig. 6, and draw B C S resting on the corners.
Fig. 8 shows the face mould. Draw the line A P, and make A D P equal A D O, Fig. 6. Draw V L through P at right angles to A P. Draw D 8 parallel to V L, make D 8 equal B 3, Fig. 7; join A 8 extended to cut V L in O; then O will be the centre. Make A B and 8 C equal A B and D C, Fig. 6. The completion of the mould will be understood. The tangent C B will equal C B, Fig. 7, if the drawing is correct.