Abstract: An instrument adapted for making perspective drawing, comprising a slider on a base plate and a link pivoted to two levers of exactly equal lengths between pivot centers and at equal distances on the slider and the link. The arrangement further includes a ruler or bar extending in a direction generally transversely to the levers and connected thereto by means of a joint structure which is slidable along the levers to any desired set position and which permits a rotational as well as a sliding motion of the ruler relative to the joint center as the angular position of the ruler relative to the levers is changed.