| rod | |
|---|---|
| Unit system | imperial/US units |
| Unit of | length |
| Conversions | |
| 1 rodin ... | ... is equal to ... |
| Imperial/US units | 16+1⁄2 ft |
| metric (SI) units | 5.0292 m |
Therod,perch, orpole (sometimes alsolug) is asurveyor's tool[1] andunit of length of various historical definitions. InBritish imperial andUS customary units, it is defined as16+1⁄2feet, equal to exactly1⁄320 of amile, or5+1⁄2yards (a quarter of asurveyor's chain), and is exactly 5.0292 meters. The rod is useful as a unit of length because integer multiples of it can form oneacre of square measure (area). The 'perfect acre'[2] is a rectangular area of 43,560 square feet, bounded by sides 660 feet (afurlong) long and 66 feet (achain) wide (220 yards by 22 yards) or, equivalently, 40 rods by 4 rods. An acre is therefore 160 square rods or 10 square chains.
The nameperch derives from theAncient Roman unit, thepertica.The measure also has a relationship with the militarypike of about the same size. Both measures[1] date from the sixteenth century,[3] when the pike was still utilized in national armies. The tool has been supplanted, first bysteel tapes and later by electronic tools such as surveyor lasers and optical target devices for surveying lands. In dialectal English, the termlug has also been used, although theOxford English Dictionary states that this unit, while usually of16+1⁄2 feet, may also be of 15, 18, 20, or 21 feet.[4][5][6]
In the United States until 1 January 2023, the rod was often defined as 16.5 US survey feet, or approximately 5.029 210 058 m.[7]
In England, the perch was officially discouraged in favour of the rod as early as the 15th century;[8][better source needed] however, local customs maintained its use. In the 13th century, perches were variously recorded in lengths of 18 feet (5.49 m), 20 feet (6.1 m), 22 feet (6.71 m) and 24 feet (7.32 m); and even as late as 1820, aHouse of Commons report notes lengths of16+1⁄2 feet (5.03 m), 18 feet (5.49 m), 21 feet (6.4 m), 24 feet (7.32 m), and even 25 feet (7.62 m).[9] InIreland, a perch was standardized at 21 feet (6.4 m), making an Irish chain,furlong and mile proportionately longer by 27.27% than the "standard" English measure.[10]
Until English KingHenry VIII seized the lands of theRoman Catholic Church in 1536,[1] land measures as we now know them were essentially unknown.[1] Instead a narrative system of landmarks and lists was used. Henry wanted to raise even more funds for his wars than he'd seized directly from church property (he'd also assumed the debts of the monasteries[1]), and asJames Burke writes and quotes in the bookConnections that the English monkRichard Benese "produced a book on how to survey land using the simple tools of the time, a rod with cord carrying knots at certain intervals, waxed and resined against wet weather." Benese poetically described the measure of an acre in terms of a perch:[3]
an acre bothe of woodlande, also of fyldlande [heath] is always forty perches in length, and four perches in breadth, though an acre of woodlande be more in quantitie [value, i.e. was more valued commercially] than an acre of fyldelande
The practice of using surveyor's chains, and perch-length rods made into a detachable stiff chain, came about a century later when iron was a more plentiful and common material. Achain is a largerunit oflength measuring 66feet (20.1168 m), or 22yards, or 100links,[11] or 4 rods (20.1168meters). There are 10 chains or 40 rods in a furlong (eighth-mile), and so 80 chains or 320 rods in onestatute mile (1760 yards, 1609.344 m, 1.609344km); the definition of which waslegally set in 1593 and popularized by Royal surveyor (called the 'sworn viewer'[12])John Ogilby only after theGreat Fire of London (1666).
Anacre is defined as the area of 10 square chains (that is, an area of one chain by one furlong), and derives from the shapes of new-tech plows[2] and the desire to quickly survey seized church lands into a quantity of squares for quick sales[3] by Henry VIII's agents; buyers simply wanted to know what they were buying whereas Henry was raising cash for wars against Scotland and France.[3] Consequently, the surveyor's chain and surveyor rods or poles (the perch) have been used for several centuries in Britain and in many other countries influenced by British practices such as North America and Australia. By the time of the industrial revolution and the quickening of land sales, canal and railway surveys, et al. Surveyor rods such as used byGeorge Washington were generally made of dimensionally stable metal—semi-flexible drawn wrought iron linkable bar stock (not steel), such that the four folded elements of a chain were easily transportable through brush and branches when carried by a single man of a surveyor's crew. With a direct ratio to the length of a surveyor's chain and the sides of both an acre and a square (mile), they were common tools used by surveyors, if only to lay out a known plottable baseline in rough terrain thereafter serving as the reference line for instrumental (theodolite)triangulations.
The rod as asurvey measure was standardized byEdmund Gunter in England in 1607 as a quarter of a chain (of 66 feet (20.12 m)), or16+1⁄2 feet (5.03 m) long.
Theperch (pertica) as alineal measure in Rome (alsodecempeda) was 10 Roman feet (2.96 metres), and inFrance varied from 10 feet (perche romanie) to 22 feet (perche d'arpent—apparently1⁄10 of "the range of an arrow"—about 220 feet). To confuse matters further, by ancient Roman definition, an arpent equalled 120 Roman feet. The related unit of square measure was thescrupulum ordecempeda quadrata, equivalent to about 8.76 m2 (94.3 sq ft).[13]
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Units comparable to the perch, pole or rod were used in many European countries, with names that includeFrench:perche andcanne,German:Ruthe,Italian:canna andpertica,Polish:pręt andSpanish:canna. They were subdivided in many different ways, and were of many different lengths.
| Place | Local name | Local equivalent | Metric equivalent (meters) |
|---|---|---|---|
| Aachen | Feldmeßruthe | 16 Fuß | 4.512[14] |
| Amsterdam | Roede | 13 Voet | 3.681[15] |
| Aubenas,Ardèche | canne | 8pans | 1.985[14] |
| Baden, Grand Duchy of | Ruthe | 10 Fuß | 3.0[14] |
| Basel, Canton of | Ruthe | 16 Fuß | 4.864[14] |
| Bern, Canton of | Ruthe | 10 Fuß | 2.932[14] |
| Barcelona | canna | 8palmos | 1.581[14] |
| Braunschweig | Ruthe | 16 Fuß | 4.565[14] |
| Bremen | Ruthe | 8 Ellen or 16 Fuß | 4.626[14] |
| Brussels | Ruthe | 20 Fuß | 4.654[14] |
| Cagliari,Sardinia | canna | 10palmi | 2.322[14] |
| Calenberg Land | Ruthe | 16 Fuß | 4.677[14] |
| Cassel,Hessen | Ruthe | 14 Fuß | 4.026[14] |
| Denmark | Ruthe | 10 Fuß | 3.138[14] |
| Canton of Geneva | Ruthe | 8 Fuß | 2.598[14] |
| Hamburg | Geestruthe | 16 Fuß | 4.583[14] |
| Hamburg | Marschruthe | 14 Fuß | 4.010[14] |
| Hannover | Ruthe | 16 Fuß | 4.671[14] |
| France | Perche | 3toises | 5.847[14] |
| France | Perche (for woodland) | 3+2⁄3toises | 7.145[14] |
| Genoa | canna | 10palmi | 2.5[14] |
| Jever,Oldenburg | Ruthe | 20 Fuß | 4.377[14] |
| Mallorca | canna | 8palmos | 1.714[14] |
| Malta | canna | 8palmi | 2.08[14] |
| Mecklenburg | Ruthe | 16 Fuß | 4.655[14] |
| Menorca, but notMahón | canna | 1.599[14] | |
| Menorca, city of Mahon | canna | 8palmos | 1.714[14] |
| Messina,Sicily | canna | 8palmi | 2.113[14] |
| Montauban,Tarn-et-Garonne | canne | 8pans | 1.783[14] |
| Morocco | canna | 8palmos | 1.714[14] |
| Naples | canna (for cloth) | 8palmi | |
| Naples, Kingdom of:Apulia,Calabria,Eboli,Foggia,Lucera | percha | 7palmi | 1.838[14] |
| Naples, Kingdom of:Capua | percha | 7+1⁄5palmi | 1.892[14] |
| Naples, Kingdom of: Fiano, Naples | percha | 7+1⁄2palmi | 2.014[14] |
| Naples, Kingdom of:Caggiano,Cava,Nocera, Rocce,Salerno | percha | 7+2⁄3 palmi | 1.971[14] |
| Nuremberg, Bavaria | Ruthe | 16 Fuß | 4.861[14] |
| Oldenburg | Ruthe | 20 Fuß | 5.927[14] |
| Palermo, Sicily | canna | 8palmi | 1.942[14] |
| Parma | Pertica | 6bracci | 3.25[14] |
| Poland | Pręt | 7+1⁄2łokci or 10pręcików | 4.320[14] |
| Prussia,Rheinland | Ruthe | 12 Fuß | 3.766[14] |
| Rijnland | Roede | 12 Voet | 3.767[15] |
| Rome | canna (for cloth) | 2[14] | |
| Rome | canna (for building) | 2.234[14] | |
| Saragoza | canna | 2.043[14] | |
| Saxony | Ruthe | 16 Leipziger Fuß | 4.512[14] |
| Sweden | Ruthe | 16 Fuß | 4.748[14] |
| Tortosa | canna | 1.7[14] | |
| Tuscany, Grand-Duchy of (Florence,Pisa) | canna | 5 bracci | 2.918[14] |
| Uzès,Gard | canne | 8pans | 1.98[14] |
| Waadt, Canton of | Ruthe ortoise courante | 10 Fuß | 3[14] |
| Württemberg | Reichsruthe | 10 Fuß | 2.865[14] |
| Württemberg | old Ruthe | 16 Fuß | 4.583[14] |
| Venice, Republic of | Pertica | 6piedi | 2.084[14] |
| Zürich, Canton of | Ruthe | 10 Fuß | 3.009[14] |
In England, the rod or perch was first defined in law by theComposition of Yards and Perches, one of thestatutes of uncertain date from the late 13th to early 14th centuries:tres pedes faciunt ulnam, quinque ulne & dimidia faciunt perticam (three feet make a yard, five and a half yards make a perch).[16]
The length of the chain was standardized in 1620 byEdmund Gunter at exactly four rods.[17][18] Fields were measured in acres, which were one chain (four rods) by one furlong (in the United Kingdom, ten chains).[19]
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, whenHenry David Thoreau used it frequently when describing distances in his work,Walden.[20]
In traditionalScottish units, aScottish rood (ruid inLowland Scots,ròd inScottish Gaelic), alsofall measures 222 inches (6ells).[21]
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.[22]
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In the United States, the rod, along with the chain, furlong, and statute mile (as well as the survey inch and survey foot) were based on the pre-1959 values forUnited States customary units of linear measurement until 1 January 2023. TheMendenhall Order of 1893 defined the yard as exactly3600⁄3937 meters, with all other units of linear measurement, including the rod, based on the yard. In 1959, an international agreement (theinternational yard and pound agreement), defined the yard as the fundamental unit of length in the Imperial/USCU system, defined as exactly 0.9144 metres. However, the above-noted units, when used in surveying, may retain their pre-1959 values, depending on the legislation in each state. TheU.S. National Geodetic Survey andNational Institute of Standards and Technology have replaced the definition for the above-mentioned units by the international 1959 definition of the foot, being exactly 0.3048 meters.[23][24]
Despite no longer being in widespread use, the rod is still employed in certain specialized fields. In recreationalcanoeing, maps measureportages (overland paths where canoes must be carried) in rods; typical canoes are approximately one rod long.[25] The term is also in widespread use in the acquisition ofpipelineeasements, as the offers for an easement are often expressed on a "price per rod".[26]
In theUnited Kingdom, the sizes ofallotmentgardens continue to be measured in square poles in some areas, sometimes being referred to simply aspoles rather thansquare poles.[27]
InVermont, the defaultright-of-way width of state and town highways and trails is three rods 49 ft 6 in (15.09 m).[28] Rods can also be found on the older legal descriptions of tracts of land in theUnited States, following the "metes and bounds" method of land survey;[29] 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.[30]
The termspole,perch,rod androod have been used as units of area, andperch is also used as a unit of volume. As a unit ofarea, asquare perch (the perch being standardized to equal16+1⁄2 feet, or5+1⁄2 yards) is equal to asquare rod,30+1⁄4 square yards (25.29square metres) or1⁄160 acre. There are 40 square perches to arood (for example a rectangular area of 40 rods times one rod), and 160 square perches to anacre (for example a rectangular area of 40 rods times 4 rods). This unit is usually referred to as aperch orpole even thoughsquare perch andsquare pole were the more precise terms.Rod was also sometimes used as a unit of area to refer to a rood.
However, in the traditional French-based system in some countries, 1 squareperche is 42.21 square metres.
As of August 2013, perches and roods are used as government survey units inJamaica.[citation needed] They appear on most property title documents. The perch is also in extensive use inSri Lanka, being favored even over the rood and acre in real estate listings there.[31] Perches were informally used as a measure inQueenslandreal estate until the early 21st century, mostly for historical gazetted properties in older suburbs.[32]
A traditional unit of volume for stone and other masonry. A perch of masonry is the volume of a stone wall one perch (16+1⁄2 feet or 5.03 metres) long, 18 inches (45.7 cm) high, and 12 inches (30.5 cm) thick. This is equivalent to exactly24+3⁄4 cubic feet (0.92 cubic yards; 0.70 cubic metres; 700 litres).
There are two different measurements for a perch depending on the type of masonry that is being built:
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