Dumpy Level And Tripod Stand
Dumpy level And Tripod Stand:
A dumpy level, builder's auto level, leveling instrument, or automatic level is an optical instrument used to establish or verify points in the same horizontal plane. It is used in surveying and building with a vertical staff to measure height differences and to transfer, measure and set heights.
Tripod Stand:
A surveyor's tripod is a device used to support any one of a number of surveying instruments, such as theodolites, total stations, levels or transits.
Uses of dumpy level:
The dumpy level is mainly used in surveying for the following purposes:
To determine relative height and distance among different locations of a surveying land.
To determine relative distance among different locations of a surveying land.
Invention:
In 1832, English civil engineer William Gravatt, who had worked with Marc Isambard Brunel and his son Isambard on the Thames Tunnel, was commissioned by Mr. H.R. Palmer to examine a scheme for the South Eastern Railway's route from London to Dover. Forced to use the then conventional Y level during the work, Gravatt devised the more transportable and easier to use dumpy level.
Operation of Dumpy level:
The level instrument is set up on a tripod and, depending on the type, either roughly or accurately set to a leveled condition using foot screws (leveling screws). The operator looks through the eyepiece of the telescope while an assistant holds a tape measure or graduated staff vertical at the point of measurement. The instrument and staff are used to gather and/or transfer elevations (levels) during site surveys or building construction. Measurement generally starts from a benchmark with known height determined by a previous survey, or an arbitrary point with an assumed height.
Variants of dumpy level:
The term dumpy level endures despite the evolution in design. A dumpy level is an older-style instrument that requires skill 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. Some dumpy levels will have a bubble level intrinsic to their design which ensures an accurate level.
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 instrument's 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 instrument's adjustment. As an example, the identical effect can be had with a standard builder's level by rotating it through 180° and comparing the difference between spirit level bubble positions.
An automatic level, self-leveling level, or builder's auto level includes an internal compensator mechanism (a swinging prism) that, when set close to level, automatically removes any remaining variation. This reduces the need to set the instrument truly level, as with a dumpy or tilting level. Self-levelling instruments are the preferred instrument on building sites, construction, and during surveying due to ease of use and rapid setup time.
A digital electronic level is also set to level on a tripod and reads a bar-coded staff using electronic laser methods. The height of the staff where the level beam crosses the staff is shown on a digital display. This type of level removes interpolation of graduation by a person, thus removing a source of error and increasing accuracy. During night time, the dumpy level is used in conjunction with an autocross laser for accurate scale readings.
Dumpy level in literature:
In the first chapter of Thomas Hardy's 1887 novel The Woodlanders, the narrator states, "He knew every subtle incline of the ten miles of ground between Abbot's Cernel and Sherton—the market town to which he journeyed—as accurately as any surveyor could have learned it by a Dumpy level."
A dumpy level, builder's auto level, leveling instrument, or automatic level is an optical instrument used to establish or verify points in the same horizontal plane. It is used in surveying and building with a vertical staff to measure height differences and to transfer, measure and set heights.
Tripod Stand:
A surveyor's tripod is a device used to support any one of a number of surveying instruments, such as theodolites, total stations, levels or transits.
Uses of dumpy level:
The dumpy level is mainly used in surveying for the following purposes:
To determine relative height and distance among different locations of a surveying land.
To determine relative distance among different locations of a surveying land.
Invention:
In 1832, English civil engineer William Gravatt, who had worked with Marc Isambard Brunel and his son Isambard on the Thames Tunnel, was commissioned by Mr. H.R. Palmer to examine a scheme for the South Eastern Railway's route from London to Dover. Forced to use the then conventional Y level during the work, Gravatt devised the more transportable and easier to use dumpy level.
Operation of Dumpy level:
The level instrument is set up on a tripod and, depending on the type, either roughly or accurately set to a leveled condition using foot screws (leveling screws). The operator looks through the eyepiece of the telescope while an assistant holds a tape measure or graduated staff vertical at the point of measurement. The instrument and staff are used to gather and/or transfer elevations (levels) during site surveys or building construction. Measurement generally starts from a benchmark with known height determined by a previous survey, or an arbitrary point with an assumed height.
Variants of dumpy level:
The term dumpy level endures despite the evolution in design. A dumpy level is an older-style instrument that requires skill 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. Some dumpy levels will have a bubble level intrinsic to their design which ensures an accurate level.
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 instrument's 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 instrument's adjustment. As an example, the identical effect can be had with a standard builder's level by rotating it through 180° and comparing the difference between spirit level bubble positions.
An automatic level, self-leveling level, or builder's auto level includes an internal compensator mechanism (a swinging prism) that, when set close to level, automatically removes any remaining variation. This reduces the need to set the instrument truly level, as with a dumpy or tilting level. Self-levelling instruments are the preferred instrument on building sites, construction, and during surveying due to ease of use and rapid setup time.
A digital electronic level is also set to level on a tripod and reads a bar-coded staff using electronic laser methods. The height of the staff where the level beam crosses the staff is shown on a digital display. This type of level removes interpolation of graduation by a person, thus removing a source of error and increasing accuracy. During night time, the dumpy level is used in conjunction with an autocross laser for accurate scale readings.
Dumpy level in literature:
In the first chapter of Thomas Hardy's 1887 novel The Woodlanders, the narrator states, "He knew every subtle incline of the ten miles of ground between Abbot's Cernel and Sherton—the market town to which he journeyed—as accurately as any surveyor could have learned it by a Dumpy level."
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