Compass (drawing tool)

Prior to computerization, compasses and other tools for manual drafting were often packaged as a set[1] with interchangeable parts.

[citation needed] Today those facilities are more often provided by computer-aided design programs, so the physical tools serve mainly a didactic purpose in teaching geometry, technical drawing, etc.

Compasses are usually made of metal or plastic, and consist of two "legs" connected by a hinge which can be adjusted to allow changing of the radius of the circle drawn.

The hinge can be adjusted, depending on desired stiffness; the tighter the hinge-screw, the more accurate the compass's performance.

The better quality compass, made of metal, has its piece of pencil lead specially sharpened to a "chisel edge" shape, rather than to a point.

Some people who find this action difficult often hold the compasses still and move the paper round instead.

The most rigorous definition of this abstract tool is the "collapsing compass"; having drawn a circle from a given point with a given radius, it disappears; it cannot simply be moved to another point and used to draw another circle of equal radius (unlike a real pair of compasses).

As such it finds a place in logos and symbols such as the Freemasons' Square and Compasses and in various computer icons.

English poet John Donne used the compass as a conceit in "A Valediction: Forbidding Mourning" (1611).