Dumpy Levels
A dumpy level is an optical instrument used in surveying to transfer, measure or set horizontal levels, as well as make distance measurements (distance is usually only accurate to around 100mm).
The level instrument is set up on a tripod and, depending on the type, either roughly or accurately set to a levelled condition using foot screws (levelling screws). This levelling component is known as the ‘tribrach stage’. The operator looks through the eyepiece of the telescope while an assistant holds a graduated staff (E staff) vertical at the point being measured. The instrument and staff are used to gather and/or transfer elevations (levels). Measurement generally starts from a benchmark with known height determined by a previous survey, or an arbitrary point with an assumed height.
An auto level includes an internal compensator mechanism (a swinging prism) that, when set close to level, automatically removes any remaining variation from level. This reduces the need to set the instrument truly level. Self-levelling instruments are the preferred instrument on building sites, construction and surveying due to ease of use and rapid setup time.
Please see our Auto & Digital Levels page for more information.