Rod (unit)
and a
pole. The lengths of the
perch (one rod) and
chain (four rods) were standardized in 1607 by
Edmund Gunter.
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.
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 is still in use as a unit of measure in certain specialised fields. In recreational
canoeing, maps measure
portages (overland paths where canoes must be carried) in rods. 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 in rods.
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.
# 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.
*
furlong*
perch (volume) for a related unit of volume with the same name.
* In the episode of
The Simpsons entitled ‘
A Star is Burns’,
Grampa Simpson uttered: “My car gets forty rods to the
hogshead, and that's the way I likes it!” That 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 mpg (or about 10.48 feet per gallon) or 118,500 L/100 km.
