|
Levelling Staff
A level staff, also called levelling rod, is a graduated wooden or aluminium rod, used with a levelling instrument to determine the difference in height between points or heights of points above a vertical datum. When used for stadiametric rangefinding, the level staff is called a stadia rod. Rod construction and materials Levelling rods can be one piece, but many are sectional and can be shortened for storage and transport or lengthened for use. Aluminum rods may be shortened by telescoping sections inside each other, while wooden rod sections can be attached to each other with sliding connections or slip joints, or hinged to fold when not in use. There are many types of rods, with names that identify the form of the graduations and other characteristics. Markings can be in imperial or metric units. Some rods are graduated on one side only while others are marked on both sides. If marked on both sides, the markings can be identical or can have imperial units on one side and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Graduation (instrument)
A graduation is a marking used to indicate points on a visual scale, which can be present on a container, a measuring device, or the axes of a line plot, usually one of many along a line or curve, each in the form of short line segments perpendicular to the line or curve. Often, some of these line segments are longer and marked with a numeral, such as every fifth or tenth graduation. The scale itself can be linear (the graduations are spaced at a constant distance apart) or nonlinear. Linear graduation of a scale occurs mainly (but not exclusively) on straight measuring devices, such as a rule or measuring tape, using units such as inches or millimetres. Graduations can also be spaced at varying spatial intervals, such as when using a logarithmic, for instance on a measuring cup, can vary in scale due to the container's non- cylindrical shape. Graduations along a curve Circular graduations of a scale occur on a circular arc or limb of an instrument. In some cases, non-ci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Measuring Rod
A measuring rod is a tool used to physically length measurement, measure lengths and surveying, survey areas of various sizes. Most measuring rods are round or square sectioned; however, they can also be flat boards. Some have markings at regular intervals. It is likely that the measuring rod was used before the line, chain or steel tapes used in modern measurement. History Ancient Sumer The oldest preserved measuring rod is a copper-alloy bar which was found by the Germans, German Assyriology, Assyriologist Eckhard Unger while excavating at Nippur (pictured below). The bar dates from c. 2650 BC. and Unger claimed it was used as a measurement standard. This irregularly formed and irregularly marked ''graduated rule'' supposedly defined the ''Sumerian cubit'' as about , although this does not agree with other evidence from the statues of Gudea from the same region, five centuries later. Ancient India Rulers made from ivory were in use by the Indus Valley Civilization in what ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Staff (head) Gauge
A staff gauge or head gauge is calibrated scale which is used to provide a visual indication of liquid level. When installed perpendicular to an inclined or sloped surface, a staff gauge is usually calibrated so that the indicated level is the true vertical level. Staff gauges are commonly installed at stream gauging stations to indicate the water stage or water level. They are also used to indicate the level (and hence flow rate) in open channel primary devices (flumes or weirs); see discharge (hydrology). See also * Head (hydrology) In hydrology, the head is the point on a watercourse up to which it has been artificially broadened and/or raised by an Dam, impoundment. Above the head of the reservoir natural conditions prevail; below it the water level above the Stream bed, ... * Level staff {{water-stub Water supply Hydrology instrumentation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stadia Mark
Stadia marks, also called stadia lines or stadia hairs, are crosshairs on the reticle of a theodolite or other surveying instrument that allow stadiametric rangefinding. Etymology The term stadia mark derives from the obsolete unit of distance, the Stadion (unit), stadion, derived from the Greek measurement of a stadium. Several different stadia were defined, such as the Ancient Greek units of measurement#Length, Greek stadion and Ancient Egyptian units of measurement#Length, Egyptian stadion. Usage A typical surveyor's instrument reticle has two pairs of stadia marks. One pair are on the horizontal centreline and the other on the vertical cross hair. Each functions in the same manner and are placed for measuring on either axis. : : where * * * * * The stadia marks are set a specific length apart. This length is chosen so that there is a fixed, integer ratio between the difference of the Level_staff , rod readings and the distance from the telescope to the rod. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Retroreflector
A retroreflector (sometimes called a retroflector or cataphote) is a device or surface that reflects light or other radiation back to its source with minimum scattering. This works at a wide range of angle of incidence (optics), angle of incidence, unlike a planar mirror, which does this only if the mirror is exactly perpendicular to the wave front, having a zero angle of incidence. Being directed, the retroflector's reflection (physics), reflection is brighter than that of a diffuse reflector. Corner reflectors and Cat's eye (road), cat's eye reflectors are the most used kinds. Types There are several ways to obtain retroreflection: Corner reflector A set of three mutually perpendicular reflective surfaces, placed to form the internal corner of a cube, work as a retroreflector. The three corresponding normal vectors of the corner's sides form a basis in which to represent the direction of an arbitrary incoming ray, . When the ray reflects from the first side, say x, the ray' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ranging Rod
A ranging rod, or range rod, is a surveying instrument used for marking the position of stations, and for sightings of those stations, as well as for ranging straight lines. Initially these were made of light, thin, and straight bamboo, or of well seasoned wood such as teak, pine, or Cedrus deodara, deodar. They were shod with iron at the bottom and surmounted with a flag about 250 mm2 in size. Nowadays they are made of wood, metal, or fibreglass. The rods are usually about 30 mm in diameter and 2 or 3 m long, painted with alternating bands, such as red and white, red and yellow, or black and white, in lengths of 200 mm (i.e. one link length of metric chain), 500 mm, or 1 foot. These colours are used so that the rod can be properly sighted in case of long distance or bad weather. Ranging rods of greater length, e.g. 3 to 6 m, are called ranging or range poles, and are used for very long surveying, survey lines. Another type of ranging rod is known ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pole (surveying)
In surveying, a pole is bar made of wood or metal and normally held vertical, upon which different instruments can be mounted: a prism (surveying), prism, a GPS device, etc. It may be manufactured with a predetermined length (e.g., 2 meters) or may be graduation (instrument), graduated for different heights or stages. Technology advances have introduced tilt-compensation capability into survey poles, that allow the surveyor to measure points above ground or when the pole is off-vertical. References- See also * Level staff Surveying instruments {{civil-engineering-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Philadelphia Rod
A Philadelphia rod is a level staff used in surveying. The rod is used in levelling procedures to determine elevations and is read using a level. A Philadelphia rod consists of two sliding sections graduated in hundredths of a foot. On the front of the rod the graduation increasing from zero at the bottom. On the back of the rod the graduation decrease from 13.09 ft at the bottom to 7 ft. The division of the device in two sliding sections are devised for ease of transport. Readings of or less, and up to , can be measured. It has a rear section that slides on the front section. The rod must be fully extended, when higher measurements are needed to avoid reading errors. Distances of up to may be read. File:Reading Leveling Rod jpeg.png, Reading a Philadelphia rod File:Leveling Rod reading examples jpeg.png, Philadelphia rod reading examples The rod may be equipped with a target to increase the readable range of the rod. When the target is equipped with a Vernier scale ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vernier Scale
A vernier scale ( ), named after Pierre Vernier, is a visual aid to take an accurate measurement reading between two graduation markings on a linear scale by using mechanical interpolation, which increases resolution and reduces measurement uncertainty by using vernier acuity. It may be found on many types of instrument measuring length or measuring angles, but in particular on a vernier caliper, which measures lengths of human-scale objects (including internal and external diameters). The vernier is a subsidiary scale replacing a single measured-value pointer, and has for instance ten divisions equal in distance to nine divisions on the main scale. The interpolated reading is obtained by observing which of the vernier scale graduations is coincident with a graduation on the main scale, which is easier to perceive than visual estimation between two points. Such an arrangement can go to a higher resolution by using a higher scale ratio, known as the vernier constant. A ver ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dumpy Level
A level is an optical instrument used to establish or verify points in the same horizontal plane in a process known as '' levelling''. It is used in conjunction with a levelling staff to establish the relative height or levels (the vertical separation) of objects or marks. It is widely used in surveying and construction 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 optical telescope and a highly accurate bubble level 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 sh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Baak
Baak is a village in the municipality Bronckhorst in the Achterhoek part of the Dutch province of Gelderland. It stands on the Baakse Beek (literally, Brook of Baak) in the municipality of Bronckhorst, about 10 km from Zutphen. Baak was founded around 1190 as a hamlet (). The village has a quite large (for its number of inhabitants) neo-Gothic church, designed by Alfred Tepe. Behind the church its 18th-century predecessor can be found, a so-called barn church which nowadays serves as a cultural centre. In the south of the village, on the premises of a farm, stands the ruined tower of an otherwise vanished Gothic chapel from the 15th century. Within the village limits one can also find the manor ''Huize Baak'', one of the many manors in this part of the Achterhoek The Achterhoek (; ) is a cultural region and COROP area in the Eastern Netherlands. Its name (meaning "rear-corner") is geographically appropriate because the area lies in the easternmost part of the province of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interpolated
In the mathematical field of numerical analysis, interpolation is a type of estimation, a method of constructing (finding) new data points based on the range of a discrete set of known data points. In engineering and science, one often has a number of data points, obtained by sampling or experimentation, which represent the values of a function for a limited number of values of the independent variable. It is often required to interpolate; that is, estimate the value of that function for an intermediate value of the independent variable. A closely related problem is the approximation of a complicated function by a simple function. Suppose the formula for some given function is known, but too complicated to evaluate efficiently. A few data points from the original function can be interpolated to produce a simpler function which is still fairly close to the original. The resulting gain in simplicity may outweigh the loss from interpolation error and give better performance in ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
