Combined, adjustable set-square, spirit level and ruler - is pivoted at one end in middle of straight edge

摘要

The spirit level (1) has a semi-circular angle scale (2) fixed to one end. Through the centre of the angle scale is a screw (11) which clamps it to a collar (5) which can be slid along the upper edge of the graduated straight edge (4). On the edge of the collar (5) is a line which indicates the angle between the level (1) and the rule (4). The angle of an inclined plane may also be measured, by placing the rule against the plane and pivoting the level until a horizontal is found. Another attachment (7) may be used to find the 'heart-line' of a circular object placed between a horizontal and a vertical wall. An extension arm (12) which 'telescopes' out of the rule (4) may be used to clamp the rule between two walls.