The Plumb Bob

A plumb bob is a simple tool used to establish a vertical reference line. It consists of a weighted object, usually made of metal, attached to a string or cord. When the string is held or anchored at the top, gravity pulls the weight downward, causing the string to relax and align perfectly with the true vertical line. This helps builders and architects ensure walls, posts, or structures are perfectly upright. The plumb bob is a reliable, timeless instrument that provides an accurate vertical reference without the need for electronic equipment.