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. Typically one leg has a spike at its end for anchoring, and the other leg holds a drawing tool, such as a
pencil, a short length of just pencil lead or sometimes a
pen.
Handle The handle, a small knurled rod above the hinge, is usually about half an inch long. Users can grip it between their pointer finger and thumb.
Legs There are two types of leg in a pair of compasses: the straight or the steady leg and the adjustable one. Each has a separate purpose; the steady leg serves as the basis or support for the needle point, while the adjustable leg can be altered in order to draw different sizes of circles.
Hinge The screw through the hinge holds the two legs in position. 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 plated metal, is able to be finely adjusted via a small, serrated wheel usually set between the legs (see the "using a compass" animation shown above) and it has a (dangerously powerful) spring encompassing the hinge. This sort of compass is often known as a "pair of Spring-Bow Compasses".
Needle point The needle point is located on the steady leg and serves as the center point of the circle that is about to be drawn.
Pencil lead The pencil lead draws the circle on a particular paper or material. Alternatively, an ink
nib or attachment with a
technical pen may be used. 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.
Adjusting nut This holds the pencil lead or pen in place. ==Uses==