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The Y level or wye level is the oldest and bulkiest of the older style optical instruments. A low-powered telescope is placed in a pair of clamp mounts, and the instrument then leveled using a spirit level, which is mounted parallel to the main telescope. The term dumpy level (also builder's level) endures despite the evolution in design. They ...
English: A diagram showing an automatic level, or "Dumpy" level, which compensates for small deviations in the inclination of the instrument by use of a swinging prism. Thus, the light ray will always be horizontal.
The dumpy level was developed by English civil engineer William Gravatt, while surveying the route of a proposed railway line from London to Dover. More compact and hence both more robust and easier to transport, it is commonly believed that dumpy levelling is less accurate than other types of levelling, but such is not the case.
Common levelling instruments include the spirit level, the dumpy level, the digital level, and the laser level. Levelling staff – specialized measuring stick or vertical staff used with the dumpy level, held by a second person while the operator of the level looks through it and takes readings off of the staff. Also call a rod.
The pibal theodolite uses a prism to bend the optical path by 90 degrees so the operator's eye position does not change as the elevation is changed through a complete 180 degrees. The theodolite is typically mounted on a rugged steel stand, set up so it is level and pointed north, with the altitude and azimuth scales reading zero degrees.
Dumpy level; Engineer's chain; Geodimeter; Graphometer; Groma (surveying) Laser scanning; Level; Level staff; Measuring tape; Plane table; Pole (surveying) Prism (surveying) (corner cube retroreflector) Prismatic compass (angle measurement) Ramsden surveying instruments; Ranging rod; Surveyor's chain; Surveyor's compass; Tachymeter (surveying ...
Combining a spirit level with an optical telescope results in a tilting level or dumpy level. [5] These leveling instruments as used in surveying to measure height differences over larger distances. A surveyor's leveling instrument has a spirit level mounted on a telescope (perhaps 30 power) with cross-hairs, itself mounted on a tripod. The ...
In 1914 and 1915, the Forestry Quarterly published a series of articles on the use of the Abney level. [6] [7] [8] These tutorial articles remain useful today, but the primary reference for usage is the 1927 Abney Level Handbook. [3] The Abney level is typically used at the eye height of the surveyor, either hand-held or mounted on a staff at ...