Plum Bob
A plumb bob is a vertical hanging weight with a pointed tip at the bottom, used in construction and carpentry to establish a true vertical reference line, known as a plumb line. The weight, typically made of metal or another dense material, is suspended from a string or line and allowed to hang freely. Gravity causes the plumb bob to align itself with the Earth's gravitational pull, indicating a precise vertical direction. This tool is commonly employed to ensure accuracy in tasks such as aligning walls, checking the verticality of structures, and determining the depth of wells or boreholes.