In Fig. 249 we have an example of steps ascending and descending. First set out the ground-plan, and find its vanishing point _S_ (point of sight). Through _S_ draw vertical _BA_, and make _SA_ equal to _SB_. Set out the first step _CD_. Draw _EA_, _CA_, _DA_, and _GA_, for the ascending guiding lines. Complete the steps facing us, at central line _OO_. Then draw guiding line _FB_ for the descending steps (see Rule 8).
First draw the base _ABCD_ (Fig. 251) at the required angle by the new method (Fig. 250). Produce _BC_ to the horizon, and thus find vanishing point _V_. At this point raise vertical _VV·_. Construct first step _AB_, refer its height at _B_ to line of heights hI on left, and thus obtain height of step at _A_. Draw lines from _A_ and _F_ to _V·_. From _n_ draw diagonal through _O_ to _G_. Raise vertical at _O_ to represent the height of the next step, its height being determined by the scale of heights at the side. From _A_ and _F_ draw lines to _V·_, and also similar lines from _B_, which will serve as guiding lines to determine the height of the steps at either end as we raise them to the required number.
First draw the ground-plan _G_ at the required angle, using vanishing and measuring points. Find the height _hH_, and width at top _HH·_, and draw the sides _HA_ and _H·E_. Note that _AE_ is wider than _HH·_, and also that the back legs are not at the same angle as the front ones, and that they overlap them. From _E_ raise vertical _EF_, and divide into as many parts as you require rounds to the ladder. From these divisions draw lines 1 1, 2 2, &c., towards the other vanishing point (not in the picture), but having obtained their direction from the ground-plan in perspective at line _Ee_, you may set up a second vertical _ef_ at any point on _Ee_ and divide it into the same number of parts, which will be in proportion to those on _EF_, and you will obtain the same result by drawing lines from the divisions on _EF_ to those on _ef_ as in drawing them to the vanishing point.
This figure shows the other method of drawing steps, which is simple enough if we have sufficient room for our vanishing points.
The manner of working it is shown at Fig. 124.
STEPS AND A DOUBLE CROSS DRAWN BY MEANS OF DIAGONALS AND ONE VANISHING POINT