[Illustration: Fig. 46.]
Let _P_, Fig. 46., be the vanishing-point of the inclined line, and
_V_ the vanishing-point of the relative horizontal.
Find the dividing-points of the relative horizontal, _D_ and _D′_.
Through _P_ draw the horizontal line _XY_.
With center _P_ and distance _DP_ describe the two arcs _DX_ and
_D′Y_, cutting the line _XY_ in _X_ and _Y_.