Rod (length)

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1 rod =
SI units
5.02920 m 502.920 cm
US customary / Imperial units
5.50000 yd 16.5000 ft

The rod is a unit of length equal to 5.5 yards, 11 cubits, 5.0292 metres, 16.5 feet, or 1⁄320 of a statute mile. A rod is the same length as a perch[1] and a pole. The lengths of the perch (one rod) and chain (four rods) were standardized in 1607 by Edmund Gunter. In old English, the term lug is also used.[2][3]

The length is equal to the standardized length of the ox goad used by medieval English ploughmen; fields were measured in acres which were one chain (four rods) by one furlong (in the United Kingdom, ten chains).

Because the furlong was "one plough's furrow long" and a furrow was the length a plough team was to be driven without resting, the length of the furlong and the acre vary regionally, nominally due to differing soil types. In England the acre was 4,840 square yards, but in Scotland it was 6,150 square yards and in Ireland 7,840 square yards. In all three countries, fields were divided in acres and thus the furlong became a measure commonly used in horse racing, archery, and civic planning.

A sign at the City Hall in Münster, Germany noting that the bar shown is one "Prussian Half Rod" long
A sign at the City Hall in Münster, Germany noting that the bar shown is one "Prussian Half Rod" long

The rod was still in use as a common unit of measurement in the mid-1800s, when Henry David Thoreau used it frequently when describing distances in his work Walden.

Bars of metal one rod (16.5 feet) long were used as standards of length in surveying land in the past. One example of a surveyor's rod is a one piece metal bar encased in a cylindrical canvas tube (to keep the sun from heating it and making it increase in length) with a piece of the semiprecious gemstone jasper at each end of the rod (to prevent wear of the metal bar).

The rod was phased out as a unit of measurement that could legally be used in the United Kingdom as part of a ten year metrication process that began on 24 May 1965[4]. Its modern-day obscurity was used as an indicator of Grampa Simpson's age in the episode entitled ‘A Star Is Burns’, when he uttered: “My car gets forty rods to the hogshead, and that's the way I likes it!” This translates into 504 U.S. gallons per mile, or about 1.2 litres per metre. In units more normal for this purpose, it is 0.00198 miles per US gallon (or about 10.48 feet per gallon) or 118,500 L/100 km.

Despite no longer being in widespread use, the rod is still used in certain specialised fields. In recreational canoeing, maps measure portages (overland paths where canoes must be carried) in rods[citation needed]. This is thought to persist due to the rod approximating the length of a typical canoe. In the United Kingdom, the sizes of allotment gardens continue to be measured informally in square rods (although rental prices must be quoted in metric units). In Vermont, the default width of state and town highways and trails is three rods. (VSA Title 17 §702) Rods can also be sometimes found on the legal descriptions of properties in the United States that used the "Metes and bounds" method of land survey;[5] 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.

[edit] Notes

  1. ^ A perch is also a unit of area of land = 1 square rod, and a unit of cubic measure of stonework, usually = 16.5 feet by 1 foot by 1.5 feet = 24.75 cubic feet.
  2. ^ Anglo-Saxon And Roman To Metrics Conversion
  3. ^ Units: L
  4. ^ Department of Trade and Industry
  5. ^ Shelton, Neil. How to Read Land Descriptions. homestead.org. Retrieved on 2008-05-07.

[edit] See also