From Wikipedia, the free encyclopedia

Dumpy level in use on a construction site

Leveler for use by hand

A dumpy level, builders auto level, leveling instrument or automatic level is an instrument used in surveying and building to transfer, measure, or set horizontal levels.

It is an instrument that is set up on a tripod and, depending on the type, either roughly or accurately set to a leveled condition. One operator looks through the sight while the other holds a tape measure or graduated staff at the position to be measured. They are used to gather and/or transfer elevations (or levels) during site surveys or building construction. They generally start from a reference point known as a benchmark, this may be a value from a known survey point, or an arbitrary point used as a once off.

A dumpy level is an older style instrument that requires skilled use to set accurately. The instrument requires to be set level (see spirit level) in each quadrant, to ensure it is accurate through a full 360 ° traverse.

A variation on the dumpy and one that was often used by surveyors, where greater accuracy and error checking was required, is a tilting level. This instrument allows the telescope to be effectively flipped through 180 °, without rotating the head. The telescope is hinged to one side of the instruments axis, flipping it involves lifting to the other side of the central axis (thereby inverting the telescope). This action effectively cancels out any errors introduced by poor setup procedure or errors in the instruments adjustment. As an example, the identical effect can be had with a standard builders level by rotating it through 180 ° and comparing the difference between spirit level bubble positions.

An automatic level, or builders auto level, involves an internal mechanism (a swinging prism) that once set close to level, will automatically compensate for any slight, remaining variation. This cancels the need to set the instrument truly level, as with a dumpy or tilting level. They are now the preferred instrument on building sites, construction and surveying due to ease-of-use and rapid setup time.

The term dumpy level endures despite the evolution in design.

• Theodolite

• Dumpy level, from a surveying instrument collection.
• Levels, examples and usage.
• Checking a level Retired builder's help site. (non commercial).