The 49th parallel of north latitude forms part of the international boundary between Canada and the United States from Manitoba to British Columbia on the Canadian side and from Minnesota to Washington on the U.S. side. Its use as a border is a result of the Anglo-American Convention of 1818 and the Oregon Treaty of 1846. ...more on Wikipedia about "49th parallel north"
Aerial survey is a method of collecting information by utilising aerial photography or from remote sensing technology using other bands of the electromagnetic spectrum, such as infrared, gamma, or ultraviolet. It can also refer to the chart or map made by analysing a region from the air. This is typically done using satellites, aircraft, balloons, or kites. Aerial surveys can provide information on many things not visible from the ground. ...more on Wikipedia about "Aerial survey"
In United States land surveyal, a baseline is the principal east-west line that divides townships between north and south. The baseline meets its corresponding meridian at the point of origin, or initial point, for the land survey. For example, the baseline for Nebraska and Kansas is shared as the border for both states, at the 40th parallel. ...more on Wikipedia about "Baseline (surveyal)"
A benchmark is a point of reference for a measurement. In surveying a benchmark is set by a surveyor to mark a point of known vertical elevation. These marks may be chiseled into a wall or they may be small brass or aluminium disks, concrete posts, iron pins or bolts that are permanently attached to a stable foundation. In all cases the mark is used by subsequent surveyors to establish the elevation of nearby points. ...more on Wikipedia about "Benchmark (surveying)"
A cadastre is a register of the real property of a country, with details of the area, the owners and the value. ...more on Wikipedia about "Cadastre"
The chain is an English unit of length. It is defined as 66 feet (20.1168 metres). It is also known as the surveyor's chain, Gunter's chain or land chain. ...more on Wikipedia about "Chain (unit)"
A dioptra is a instrument dating back to ancient Greece, at least 300 B.C.E. It is said to have been "long used by Greek astronomers", such as Hipparchus(sometimes credited with inventing it). Adapted to surveying, the dioptra is similar to the theodolite, or "surveyor's transit" (which dates to the 16th century). It is a more accurate version of the Groma. ...more on Wikipedia about "Dioptra" www.shortopedia.com - forget the rest.
A dumpy level, builders auto level or automatic level is an instrument used in surveying and building to transfer, measure, or set horizontal levels. ...more on Wikipedia about "Dumpy level"
Ellicott’s Stone is a boundary marker placed on April 10, 1799 by a joint U.S.- Spanish survey party. It marked the east/west boundary between the U.S. Mississippi Territory and Spanish West Florida, as set forth in the 1795 Pinckney Treaty (more formally called the Treaty of San Lorenzo). The treaty specified that 31 degrees north latitude —in the middle of Alabama— defined the northern boundary between U.S. and Spanish territory. ...more on Wikipedia about "Ellicott's Stone"
A frame of reference is the perspective from which a system is observed. In physics, it provides a set of axes relative to which an observer can measure the position and motion of all points in a system, as well as the orientation of objects in it. There are two types of reference frames: inertial and non-inertial. An inertial frame of reference travels at a constant velocity, which means that Newton's first law (inertia) holds true. A non-inertial frame of reference, such as a moving car or a rotating carousel, accelerates. Therefore, Newton’s first law does not hold true, as objects appear to accelerate without the appropriate forces. ...more on Wikipedia about "Frame of reference"
Gromatici (from groma or gruma, a surveyor's pole), or agrimensores, the name for land-surveyors amongst the Romans. ...more on Wikipedia about "Gromatici"
The heliotrope is an instrument that reflects sunlight over great distances to mark the positions of participants in a land survey. The heliotrope was invented by the German mathematician Carl Friedrich Gauss. ...more on Wikipedia about "Heliotrope (instrument)"
In surveying, the Jacob's staff or cross-staff is a single straight rod or staff, pointed and iron-shod at the bottom, for penetrating the ground. It also has a socket joint at the top, used, instead of a tripod, for supporting a compass. ...more on Wikipedia about "Jacob's staff"
A laser line level is a tool combining a spirit level and/or pendulum with a laser to indicate a levelled line against a surface. ...more on Wikipedia about "Laser line level" Just shortopedia way
The Mason–Dixon Line (or "Mason and Dixon's Line") is a line of demarcation between states in the United States. Originally, the Mason–Dixon line was just part of the boundary between Pennsylvania and Maryland, but it has been extended in popular usage to indicate the division between the U.S. Northern states and the U.S. Southern states, both in the American Civil War and in the sense of the cultural differences that persist to this day. In this broader sense, there is not universal agreement on the exact location or extent of the line. ...more on Wikipedia about "Mason-Dixon line"
Ordinance Datum (O.D. or OD) is a mapping term used by the UK's Ordinance Survey as a reference point for the height data on Ordinance Survey maps. Simply, it is mean sea level—or, more specifically, it is the mean sea level at Newlyn in Cornwall as calculated between 1915 and 1921. ...more on Wikipedia about "Ordinance Datum"
A plat is a map, drawn to scale, showing how a piece of land is divided. Township plats were created by General Land Office surveyors to show the distance and bearing between survey corners, and sometimes topographic or vegetation information. City, town or village plats are divided into lots with streets and alleys, usually for the purpose of selling the described lots; this is known as subdivision. After a plat is filed, legal descriptions can refer to lot numbers rather than portions of sections. Plats can also legally dedicate land for road and other rights-of-way. ...more on Wikipedia about "Plat"
The Principal Triangulation of Britain was a triangulation project carried out between 1783 and about 1853 at the instigation of the Director of the Ordnance Survey General William Roy (1726-1790). ...more on Wikipedia about "Principal Triangulation of Great Britain"
The Ramsden theodolite is a large theodolite ( American English: transit) which was specially constructed for use in the first Ordnance Survey of Southern Britain. The theodolite was commissioned from Jesse Ramsden, a leading Yorkshire instrument maker, who had developed the technique of dividing angular scales accurately to within a second of arc. The instrument took three years to build, and had a base circle of 3 ft (914 mm) - it was also known as the Great or 36 inch theodolite. ...more on Wikipedia about "Ramsden theodolite"
In 1935, the new Director General of the Ordnance Survey, Major-General Malcolm MacLeod, started the retriangulation of Great Britain, an immense task which involved erecting concrete triangulation pillars ( trig points) on prominent hilltops throughout Great Britain. ...more on Wikipedia about "Retriangulation of Great Britain"
A rotating frame of reference is a coordinate system that describes how physics appears when measured against a hypothetical network of rigid rulers extending from a rotating body. If a body is described as travelling in a straight line with respect to an inertial reference frame, then when the same physics is described from a rotating reference frame, the same body's motion will usually seem to be following a curved path. ...more on Wikipedia about "Rotating reference frame" This text is made on www.shortopedia.com
In U.S. land surveying, a section is an area nominally one mile square, containing 640 acres (2.6 km²). Nominally, 36 sections make up a survey township on a rectangular grid. As the townships are based on meridians (of longitude) which converge towards the north pole, some sections which vary slightly in size are necessary to compensate. These unusually sized sections generally occur at the northern- or western-most edges of townships. ...more on Wikipedia about "Section (U.S. land surveying)"
Spirit leveling is a technique for determining differences in height between points on the Earth's surface. It works by using an instrument, a spirit level, consisting of a telescope and a tube level like that used by carpenters, rigidly connected. When the bubble in the tube level is in the middle, the telescope's optical axis (collimation axis) will point exactly in the direction of the local horizontal. ...more on Wikipedia about "Spirit leveling"
Surveying is the art and science of accurately determining the position of points and the distances between them. These points are usually, but not exclusively, associated with positions on the surface of the Earth, and are often used to establish land boundaries for ownership or governmental purposes. ...more on Wikipedia about "Surveying"
Tacheometry (from Greek, quick measure), is a system of rapid surveying, by which the positions, both horizontal and vertical, of points on the earth surface relatively to one another are determined without using a chain or tape or a separate levelling instrument. The ordinary methods of surveying with a theodolite, chain, and levelling instrument are fairly satisfactory when the ground is pretty clear of obstructions and not very precipitous, but it becomes extremely cumbrous when the ground is much covered with bush, or broken up by ravines. Chain measurements are then both slow and liable to considerable error; the levelling, too, is carried on at great disadvantage in point of speed, though without serious loss of accuracy. These difficulties led to the introduction of tacheometry, in which, instead of the pole formerly employed to mark a point, a staff similar to a level staff is used. This is marked with heights from the foot, and is graduated according to the form of tacheometer in use. The azimuth angle is determined as formerly. The horizontal distance is inferred either from the vertical angle included between two well-defined points on the staff and the known distance between them, or by readings of the staff indicated by two fixed wires in the diaphragm of the telescope. The difference of height is computed from the angle of depression or elevation of a fixed point on the staff and the horizontal distance already obtained. Thus all the measurements requisite to locate a point both vertically and horizontally with reference to the point where the tacheometer is centred are determined by an observer at the instrument without any assistance beyond that of a man to hold the staff. ...more on Wikipedia about "Tacheometry"
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