Rod

It has been suggested that Perch (unit) be merged into this article or section. (Discuss) Proposed since February 2012.

It has been suggested that Rood (unit) be merged into this article or section. (Discuss) Proposed since February 2012.

It has been suggested that Rood (Scots) be merged into this article or section. (Discuss) Proposed since February 2012.

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The rod is a unit of length equal to 5½ yards, 16½ feet or ⅟320th of a statute mile. Since the adoption of the international yard on 1 July 1959, it has been equivalent to exactly 5.0292 metres. A rod is the same length as a perch or a pole. In old English, the term lug is also used.^[1][2]

History

In ancient cultures

The Ancient Roman units of measurement of length included a rod or pertica (also decempeda) of 10 pedes, which was equivalent to about 2.96 m; the related unit of square measure was the scrupulum or decempeda quadrata, equivalent to about 8.76 m².^[3]

In continental Europe

A standard at the City Hall in Münster, Germany from 1816; the bar shown is one "Prussian Half Rod" long.

Units comparable to the perch, pole or rod were used in many European countries, with names that include French: perche and canne, German: Ruthe, Italian: canna and pertica, Polish: prȩt and Spanish: canna. They were subdivided in many different ways, and were of many different lengths. One source from 1830^[4] lists the following:

In Britain

In England, the rod is first defined in law by the Composition of Yards and Perches, one of the Statutes of uncertain date from the late 13th to early 14 centuries.

The length of the chain was standardized in 1620 by Edmund Gunter at exactly 4 rods.^[5][6]Fields were measured in acres, which were one chain (four rods) by one furlong (in the United Kingdom, ten chains).^[7]

Bars of metal one rod long were used as standards of length when surveying land. The rod was still in use as a common unit of measurement in the mid-19th century, when Henry David Thoreau used it frequently when describing distances in his work Walden.^[8]

Modern use

The rod was phased out as a legal unit of measurement in the United Kingdom as part of a ten-year metrication process that began on 24 May 1965.^[9]

In the USA, the rod, along with the chain, furlong, and statute mile (as well as the survey inch and survey foot) are based on the pre-1959 values for United States customary units of linear measurement. The Mendenhall Order of 1893 defined the yard as exactly 3600/3937 meters, with all other units of linear measurement, including the rod, based on the yard. In the post-1959 system, the fundamental unit of length is the inch, defined as exactly 2.54 centimeters. The above-noted units, used in surveying, retain their pre-1959 values.^[10]

Despite no longer being in widespread use, the rod is still employed in certain specialized fields. In recreational canoeing, maps measure portages (overland paths where canoes must be carried) in rods; typical canoes are approximately one rod long.^[11] In the United Kingdom, the sizes of allotment gardens continue to be measured in square poles in some areas, sometimes being referred to simply as poles rather than square poles.^[12]

In Vermont, the default right-of-way width of state and town highways and trails is three rods (15.0876 m).^[13] Rods can also be found on the older legal descriptions of tracts of land in the United States, following the "metes and bounds" method of land survey;^[14] as shown in this actual legal description of rural real estate:

LEGAL DESCRIPTION: Commencing 45 rods East and 44 rods North of Southwest corner of Southwest 1/4 of Southwest 1/4; thence North 36 rods; thence East 35 rods; thence South 36 rods; thence West 35 rods to the place of beginning, Manistique Township, Schoolcraft County, Michigan.^[15]

Area and volume

The terms pole, perch and rod have been used as units of area, and perch is also used as a unit of volume. See square perch and rood.

See also

• Perch
• Chain (unit)
• Furlong
• Imperial units
• English units
• United States customary units
• anthropic units

References