Level (optical instrument)

A level is an <a href="/facts/Optical_instrument/jB29DQNk">optical instrument</a> used to establish or verify points in the same <a href="/facts/Horizontal_plane/Hhsu9C8x">horizontal plane</a> in a process known as <a href="/facts/Levelling/sQSgmU2U">levelling</a>. It is used in conjunction with a <a href="/facts/Levelling_staff/PxBRjyXq">levelling staff</a> to establish the relative height or levels (the <a href="/facts/Vertical_separation/HpaNYcWC">vertical separation</a>) of objects or marks. It is widely used in <a href="/facts/Surveying/qchGcnRC">surveying</a> and <a href="/facts/Construction/58eqDhy9">construction</a> to measure height differences and to transfer, measure, and set heights of known objects or marks.
It is also known as a surveyor's level, builder's level, dumpy level or the historic "Y" level. It operates on the principle of establishing a visual level relationship between two or more points, for which an inbuilt <a href="/facts/Optical_telescope/dVfBR10I">optical telescope</a> and a highly accurate <a href="/facts/Bubble_level/fXQH69hY">bubble level</a> are used to achieve the necessary accuracy. Traditionally the instrument was completely adjusted manually to ensure a level line of sight, but modern automatic versions self-compensate for slight errors in the coarse levelling of the instrument, and are thereby quicker to use.
The optical level should not be confused with a <a href="/facts/Theodolite/G4ADP1bC">theodolite</a>, which can also measure angles in the vertical plane.

Level (optical instrument) open-in-new

Level (optical instrument)