Acre:   A measure of land, 160 square rods (4,480 square yards; 43,560 square feet) in whatever shape.  208.7103’ square.

Angle: The difference in direction between two convergent lines.  It may be classed as horizontal, vertical, oblique, spherical, or spheroidal, according to whether it is measured in a horizontal, vertical, or inclined plane, or in a curved surface.

Barleycorn:  An old measure of length, equal to the average length of a grain of barley; the third part of an inch.

Base line:  A surveyed line established with more than usual care, to which surveys are referred for coordination and correlation.

Bearing:  The direction of one point or object, with respect to another, where the direction of the line is expressed by the acute angle with respect to a reference meridian.  The reference direction can be North or South and the meridian may be assumed, grid, magnetic, astronomic, or geodetic.  Typical bearings are N 60º, 10’E, S 31º 17’ W, N 17º 22’ W.

Bench Mark:  A relatively permanent material object, natural or artificial, bearing a marked point whose elevation above or below an adopted datum is known.  Usually designated as a B.M., such a mark is sometimes qualified as a P.B.M. (permanent bench mark) to distinguish it from a T.B.M. (temporary or supplementary bench mark) which is a mark of less permanent character intended to serve for only a comparatively short period of time.

Boundary Monument:  A material object placed on or near a boundary line to preserve and identify the location of the boundary line on the ground.  Where is impracticable to establish a monument on or very close to a boundary line, the position of the boundary line on the ground is preserved by reference marks.  The term monument is sometimes used to include both the mark on the boundary line and the reference mark.

Cardinal Direction:  The directions on the surface of the earth-north, south, east, and west.  The term, cardinal, without qualification, is sometimes used to indicate any or all of the above directions, the context giving the exact meaning to its use.

Chain:  A unit of length used in the subdivision of public lands of the United States.  The Gunter’s chain is 66 feet long and is divided into 100 links each 7.92 inches long.  (Early chains were 50 links, or 33 feet in length.)  In its earliest construction the chain was made from iron (later, heavy steel wire) in short pieces which were bent at the end to form rings; three extra rings were placed in between the pieces, each assembly to make up 1 whole link, or 7.92 inches.  There are many wearing surfaces and other ready causes for errors in length.  The link chain was not superseded by the steel ribbon tape, in general practice, until after 1900.  The chain is a convenient length for land measurement because 10 square chains = 1 acre.

Common Law:  The body of judicial decisions developed in England and based upon immemorial usage.  It is unwritten law as opposed to statute, or written, law.  The English common law forms the foundation for the system of law in the United States.

Cubit:  A measure of length, in its origin the length of the forearm, from the elbow to the extremity of the middle finger; in English measure, 18 inches (45.72 cm.).  The ancient Egyptian cubit was 20.7 inches (52.5 cm.), and the ancient Roman cubit 17.5 inches (44.36 cm.).  The usual cubit of the ancient Greeks is stated to have been 18.22 inches (46.29 cm.), and of the Hebrews, 17.58 inches (44.65cm.).  The cubit is also known as the hath in India; covid, in the East; codo in Spain; hasta in the ancient Hindu system, etc.

Datum:  Any numerical or geometrical quantity or set of such quantities which may serve as a reference or base for other quantities.  For a group of statistical references, the plural form is data-as geographic data for a list of latitudes and longitudes.  Where the concept is geometrical and particular, rather than statistical and inclusive, the plural form is datums, as, for example, two geodetic datums have been used in the United States in recent years.

Datum, mean sea level:  A determination of mean sea level that has been adopted as a standard datum for heights or elevations.  The Sea Level Datum of 1929, the current standard datum for geodetic leveling in the United States, is based on tidal observations over a number of years at various tide stations along the coasts.

Evidence:  That which is legally submitted to a competent tribunal as a means of ascertaining the truth of any alleged matter of fact under investigation before it; means of making proof; medium of proof.

Eyott:  A small island arising in a river.

Fathom:  1)  A unit of distance equivalent to 6 feet, used primarily in marine measurements.  2)  To find the depth of something; to sound.

Flood Plain:  1)  Valley land along the course of a stream which is subject to inundation during periods of high water that exceed normal bank-full elevation.  2)  Land that is parallel to the stream with approximately level ground elevation, gentle longitudinal slope corresponding to the gradient of the stream, and very flat backslope.  3)  Natural terrain frequently consisting of low-lying timbered land, interspersed with swamp, marsh, small lakes, ponds, and bayous.

Four-pole Chain:  A pole is 16 ½ feet; a four-pole chain is therefore 66 feet.  Also termed a Gunter’s chain.

Furlong:  A measure of length equal to 1/8 mile or 220 yards.

Grantee:  A person to whom property is transferred by deed or to whom property rights are granted by a trust instrument or other document.

Grantor:  A person who transfers property by deed, or grants property rights through a trust instrument or other document.

Gravity:  1)  The gravitational force, as modified by centrifugal force due to rotation, exerted by the earth on bodies at or near its surface, resulting in their having weight.  2)  A unit of acceleration equal to the acceleration resulting from the average force of gravity at the earth’s surface.  By international agreement this unit is equal to 980.665 centimeters per second.

Great Pond:  In Maine and Massachusetts, natural ponds (lakes) having an area of more than 10 acres.

Link:  A unity of linear measure, one hundredth of a chain and equivalent to 7.92 inches.  (See also chain.)

Metes and Bounds: A method of describing land by measure of length (metes) of the boundary lines (bounds).  Most common method is to recite direction and length of each line as one would walk around the perimeter.  In general the “metes” and “bounds” can be recited by reference to record, natural or artificial monuments at the corners; and record, natural or cultural boundary lines.

Palm:  1 palm = 3 inches to 4 inches (United States); 3.94 inches (Netherlands).

Peonia:  In Spanish law.  A portion of land which was formerly given to a simple soldier on the conquest of a country.  It is now a quantity of land of different size in different provinces.  In the Spanish possessions in America it is measured 50 feet front and 100 feet deep.

Perch:  A measure of length, varying locally in different countries, but by statute in Great Britain and the United States equal to 16.5 feet.  It was used extensively in the early public land surveys and is equivalent in length to a rod or pole.

Pied:  One sixth of a toise.

Rod:  1) A measure of length containing 5 ½ yards or 16 ½ feet. 2) The corresponding square measure, called also perch; pole.  3) Any slender bar, as of wood or metal.  Specifically, a bar or staff for measuring.

Rood:  1) A square measure equal, in England and Scotland, usually to one fourth of an acre, or 40 square rods; in the Union of South Africa, to 17.07 square yards, or 14.28 square meters.  2) A linear measure varying locally, from 5 ½ to 8 yards.

Span:  1 span = 6 inches.

Survey, cadastral: A survey relating to land boundaries and subdivision, made to create units suitable for transfer or to define the limitations of title.  Derived from “cadastre”, and meaning register of the real property of a political subdivision with details of area, ownership, and value.  The term cadastral survey is now used to designate the surveys of the public lands of the United States, including retracement surveys for the identification and resurveys for the restoration of property lines; the term can also be applied properly to corresponding surveys outside the public lands, although such surveys are usually termed land surveys through preference.

Surveying, land: Land surveying is the art of science of: 1) reestablishing cadastral surveys and land boundaries based on documents of record and historical evidence; 2) planning, designing and establishing property boundaries; and 3) certifying surveys as required by statute or local ordinance such as subdivision plats, registered land surveys, judicial surveys, and space delineation.  Land surveying can include associated services such as mapping and related data accumulation; construction layout surveys; precision measurements of length, angle, elevation, area and volume; horizontal and vertical control systems; and the analysis and utilization of survey data.

Toise: A unit of length used in early geodetic surveys and equal to about 6.4 English feet.

Verst: A Russian measure of distance equal to 0.6629 mile or 1.067 km.

Westa:  Half a hide of land or 60 acres.

*All definitions taken from “Definitions of Surveying and Associated Terms” prepared by a joint committee of the American Congress on Surveying and Mapping and the American Society of Civil Engineers. 1978 (Rev.) Reprinted to 1989