Although in this figure we have taken a longer distance-point than in the previous one, we are able to draw it all within the page.
Begin by setting out the square base at the angle required. Find point _G_ by means of diagonals, and produce _AB_ to _V_, &c. Mark height of step _Ao_, and proceed to draw the steps as already shown. Then by the diagonals and measurements on base draw the second step and the square inside it on which to stand the foot of the cross. To draw the cross, raise verticals from the four corners of its base, and a line _K_ from its centre. Through any point on this central line, if we draw a diagonal from point _G_ we cut the two opposite verticals of the shaft at _mn_ (see Fig. 255), and by means of the vanishing point _V_ we cut the other two verticals at the opposite corners and thus obtain the four points through which to draw the other sides of the square, which go to the distant or inaccessible vanishing point. It will be seen by carefully examining the figure that by this means we are enabled to draw the double cross standing on its steps.
In this figure we have made use of the devices already set forth in the foregoing figures of steps, &c., such as the side scale on the left of the figure to ascertain the height of the steps, the double lines drawn to the high vanishing point of the inclined plane, and so on; but the principal use of this diagram is to show on the perspective plane, which as it were runs under the stairs, the trace or projection of the flights of steps, the landings and positions of other objects, which will be found very useful in placing figures in a composition of this kind. It will be seen that these underneath measurements, so to speak, are obtained by the half-distance.
Draw square _ABCD_ in parallel perspective. Divide each side into four, and raise verticals from each division. These verticals will mark the positions of the steps on each wall, four in number. From centre _O_ raise vertical _OP_, around which the steps are to wind. Let _AF_ be the height of each step. Form scale _AB_, which will give the height of each step according to its position. Thus at _mn_ we find the height at the centre of the square, so if we transfer this measurement to the central line _OP_ and repeat it upwards, say to fourteen, then we have the height of each step on the line where they all meet. Starting then with the first on the right, draw the rectangle _gD1f_, the height of _AF_, then draw to the central line _go_, f1, and 1 1, and thus complete the first step. On _DE_, measure heights equal to _D 1_. Draw 2 2 towards central line, and 2n towards point of sight till it meets the second vertical _nK_. Then draw n2 to centre, and so complete the second step. From 3 draw 3a to third vertical, from 4 to fourth, and so on, thus obtaining the height of each ascending step on the wall to the right, completing them in the same way as numbers 1 and 2, when we come to the sixth step, the other end of which is against the wall opposite to us. Steps 6, 7, 8, 9 are all on this wall, and are therefore equal in height all along, as they are equally distant. Step 10 is turned towards us, and abuts on the wall to our left; its measurement is taken on the scale _AB_ just underneath it, and on the same line to which it is drawn. Step 11 is just over the centre of base _mo_, and is therefore parallel to it, and its height is _mn_. The widths of steps 12 and 13 seem gradually to increase as they come towards us, and as they rise above the horizon we begin to see underneath them. Steps 13, 14, 15, 16 are against the wall on this side of the picture, which we may suppose has been removed to show the working of the drawing, or they might be an open flight as we sometimes see in shops and galleries, although in that case they are generally enclosed in a cylindrical shaft.