A variation of this tool has the plumb line hung from the top of an inverted T shape. An A-frame level with a plumb line hung from the vertex was also used to find horizontal these were used in Europe until the mid–19th century. However, if they are mounted on a suitable scale the instrument may also be used as an inclinometer to measure angles to the vertical.Īncient Egyptians used a plumb line attached to the top outer part of a tool resembling a letter E when placed against a wall, the plumb line would indicate a vertical line. Plumb bob with scale as an inclinometer Plumb bob with string in masonry workĪ plumb bob and line alone can determine only a vertical reference. Many cathedral spires, domes and towers still have brass datum marks inlaid into their floors, which signify the center of the structure above.

As the building proceeded upward, the plumb line would also be taken higher, still centered on the datum. A section of the scaffolding would hold a plumb line, which was centered over a datum mark on the floor. Until the modern age, plumb bobs were used on most tall structures to provide vertical datum lines for the building measurements. The adjective plumb developed by extension, as did the noun aplomb, from the notion of 'standing upright'. The plumb in plumb bob derives from Latin plumbum (' lead'), the material once used for the weighted bob at the end. Etymology A plumb rule from Cassells' Carpentry and Joinery A plumb square from Cassells' Carpentry and Joinery It is used with a variety of instruments (including levels, theodolites, and steel tapes) to set the instrument exactly over a fixed survey marker or to transcribe positions onto the ground for placing a marker. It is also used in surveying, to establish the nadir (opposite of zenith) with respect to gravity of a point in space. The instrument has been used since at least the time of ancient Egypt to ensure that constructions are ' plumb', or vertical. If it is used for decoration, it may be made of bone or ivory. It is typically made of stone, wood, or lead, but can also be made of other metals. It is a precursor to the spirit level and used to establish a vertical datum.

JSTOR ( November 2023) ( Learn how and when to remove this template message)Ī plumb bob, plumb bob level, or plummet, is a weight, usually with a pointed tip on the bottom, suspended from a string and used as a vertical direction as a reference line, or plumb-line.Unsourced material may be challenged and removed. Please help improve this article by adding citations to reliable sources. This article needs additional citations for verification.

Empire brass plumb bob