The acre is a unit of area in a number of different systems, including the imperial and U.S. customary systems. Its international symbol is ac.

The most commonly used acres today are the international acre and, in the United States, the survey acre. The most common use of the acre is to measure tracts of land. One international acre is equal to 4046.8564224 square metres.

During the middle ages, an acre was the amount of land that could be plowed in one day with an ox.^[1]

Description[link]

The acre is related to the square mile, with 640 acres making up one square mile. One mile is 5280 feet (1760 yards). Divisions of land area were typically based on the square mile, and fractions thereof. If the square mile is divided into quarters, each quarter has a side length of ¹⁄₂ mile (880 yards) and is ¹⁄₄ square mile in area, or 160 acres. These subunits would typically then again be divided into quarters, with each side being ¹⁄₄ mile long, and being ¹⁄₁₆ of a square mile in area, or 40 acres. In the United States, farmland was typically divided as such, and the phrase "the back 40" would refer to the 40 acre parcel to the back of the farm. Most of the US midwest is on square mile grids for surveying purposes.

One acre equals 4,840 square yards, 43,560 square feet^[2] or about 4,047 square metres (0.405 hectares) (see below). While all modern variants of the acre contain 4,840 square yards, there are alternative definitions of a yard, so the exact size of an acre depends on which yard it is based on. Originally, an acre was understood as a selion of land sized at one furlong (660 ft) long and one chain (66 ft) wide; this may have also been understood as an approximation of the amount of land an ox could plough in one day. A square enclosing one acre is approximately 69.57 yards, or 208 feet 9 inches (63.63 metres) on a side. As a unit of measure, an acre has no prescribed shape; any perimeter enclosing 43,560 square feet is an acre in size.

The acre is often used to express areas of land in the United States and in countries where the Imperial System is still in use. As of 2010^[update], the acre is not used officially in the United Kingdom. In the metric system, the hectare is commonly used for the same purpose. An acre is approximately 40% of a hectare.

Perhaps the easiest way to envisage an acre is as a rectangle measuring 88 yards by 55 yards (¹⁄₁₀ of 880 yards by ¹⁄₁₆ of 880 yards), approximately the size of a standard American football field. To be more exact, one acre is 90.75 percent of a 100 yards (91.44 metres) long by 53.33 yards (48.76 metres) wide American football field (without the end zones). The full field, including the end zones, covers approximately 1.32 acres (0.53 ha). The acre is also approximately 56.68 percent of a 105 metres (344.49 feet) long by 68 metres (223.10 feet) wide Association football (soccer) pitch. It may also be remembered as 44,000 square feet, less 1%; or as the product of 66 × 660.

International acre[link]

In 1958, the United States and countries of the Commonwealth of Nations defined the length of the international yard to be 0.9144 metres.^[3] Consequently, the international acre is exactly 4,046.8564224 square metres. Since the difference between the U.S. and International acre is only approximately 0.016 square metres (24.8 square inches), it is usually not important which one is being discussed.

U.S. survey acre[link]

The U.S. survey acre is approximately 4,046.872 609 874 252 square metres; its exact value (4046 ^13,525,426⁄_15,499,969 m²) is based on an inch defined by 1 metre = 39.37 inches exactly, as established by the Mendenhall Order. Surveyors in the United States use both international and survey feet, and consequently, both varieties of acre.^[4] Areas are seldom stated to sufficient accuracy for the different definitions to be detectable.

South Asia[link]

In India, especially in South India, residential plots are measured in cents or decimel, which is one hundredth of an acre, or 435.60 square feet (40.469 m²). In Sri Lanka the division of an acre into 160 perches or 4 roods is common.^{[citation needed]}

Equivalence to other units of area[link]

1 international acre is equal to the following metric units:

• 4,046.8564224 square metres
• 0.40468564224 hectare (A square with 100 m sides has an area of 1 hectare.)

1 United States survey acre is equal to:

• 4,046.87261 square metres
• 0.404687261 hectare

1 acre (both variants) is equal to the following customary units:

• 66 feet × 660 feet (43,560 square feet)
• 1 chain × 10 chains (1 chain = 66 feet = 22 yards = 4 rods = 100 links)
• 1 acre is approximately 208.71 feet × 208.71 feet (a square)
• 4,840 square yards
• 160 perches. A perch is equal to a square rod (1 square rod is 0.00625 acre)
• 10 square chains
• 4 roods
• A chain by a furlong (chain 22 yards, furlong 220 yards)
• ¹⁄₆₄₀ (0.0015625) square mile (1 square mile is equal to 640 acres)

Historical origin[link]

Farm-derived units of measurement:

1. The rod is a historical unit of length equal to 5½ yards. It may have originated from the typical length of a mediaeval ox-goad.
2. The furlong (meaning furrow length) was the distance a team of oxen could plough without resting. This was standardised to be exactly 40 rods.
3. An acre was the amount of land tillable by one man behind one ox in one day. Traditional acres were long and narrow due to the difficulty in turning the plough.
4. An oxgang was the amount of land tillable by one ox in a ploughing season. This could vary from village to village, but was typically around 15 acres.
5. A virgate was the amount of land tillable by two oxen in a ploughing season.
6. A carucate was the amount of land tillable by a team of eight oxen in a ploughing season. This was equal to 8 oxgangs or 4 virgates.

The word acre is derived from Old English æcer originally meaning "open field", cognate to west coast Norwegian ækre and Swedish åker, German Acker, Dutch akker, Latin ager, and Greek αγρός (agros).

The acre was approximately the amount of land tillable by one man behind an ox in one day. This explains one definition as the area of a rectangle with sides of length one chain and one furlong. A long narrow strip of land is more efficient to plough than a square plot, since the plough does not have to be turned so often. The word "furlong" itself derives from the fact that it is one furrow long.

Before the enactment of the metric system, many countries in Europe used their own official acres. These were differently sized in different countries, for instance, the historical French acre was 4,221 square metres, whereas in Germany as many variants of "acre" existed as there were German states.

Statutory values for the acre were enacted in England, and, subsequently, the United Kingdom, by acts of:

• Edward I,
• Edward III,
• Henry VIII,
• George IV and
• Queen Victoria – the British Weights and Measures Act of 1878 defined it as containing 4,840 square yards.

Historically, the size of farms and landed estates in the United Kingdom was usually expressed in acres (or acres, roods, and perches), even if the number of acres was so large that it might conveniently have been expressed in square miles. For example, a certain landowner might have been said to own 32,000 acres of land, not 50 square miles of land.

Other acres[link]

• Customary acre - The customary acre was a measure of roughly similar size to the acre described above, but it was subject to considerable local variation similar to the variation found in carucates, virgates, bovates, nooks, and farundels. However, there were more ancient measures that were also farthingales. These may have been multiples of the customary acre, rather than the statute acre.
• Builder's acre - In U.S. construction and real estate development, an area of 40,000 square feet. Used to simplify math and for marketing, it is nearly 10% smaller than a survey acre.
• Scottish acre, one of a number of obsolete Scottish units of measurement
• Irish acre = 7,840 square yards
• Cheshire acre = 10,240 square yards^[5]
• Roman acre = 1,260 square metres
• God's Acre – a synonym for a churchyard.^[6]

See also[link]

• Anthropic units
• Conversion of units
• Acre-foot
• Spanish customary units
• Quarter acre
• French arpent—also used in Louisiana as length and area unit of measure
• a Morgen ("morning") of land is usually set at ²⁄₃ of a Tagwerk ("day work") of ploughing with an ox

References[link]

External links[link]

Wikisource has the text of the 1911 Encyclopædia Britannica article Acre (land measure).

• The Units of Measurement Regulations 1995 (United Kingdom)
• Cockeyed.com presents "How much is inside an acre?"

This biographical article needs additional citations for verification. Please help by adding reliable sources. Contentious material about living persons that is unsourced or poorly sourced must be removed immediately, especially if potentially libelous or harmful. (October 2009)

Marcelo Adnet
Birth name	Marcelo França Adnet
Born	(1981-09-05) September 5, 1981 (age 30) Rio de Janeiro, RJ,  Brazil
Nationality	Brazilian
Field	Actor, VJ for MTV Brasil, Comedian

Marcelo França Adnet (born in Rio de Janeiro, September 5, 1981) is a Brazilian actor, comedian and VJ.^[1] He currently has two TV shows: Adnet ao vivo ("Adnet live"), and Comédia MTV ("MTV Comedy"). He was named by Época Magazine one of the 100 most influential Brazilians in 2009.

Adnet holds a degree in Journalism at PUC-Rio, but his career as a comedian began while in college when a friend, (Fernando Caruso), invited him to make an improvisation play, Z.E. Zenas Emprovisadas, which debuted in 2003 and is still thriving in Rio de Janeiro and São Paulo. He stands out for the imitations he often creates around famous personalities. He worked on Multishow cable television channel, owned by Rede Globo, before going to MTV as a result of his performance in Rockgol. Marcelo is married to his co-worker, MTV, VJ and comedian Dani Calabresa.

References[link]

This article about a Brazilian actor or actress is a stub. You can help Wikipedia by expanding it. v t e

The 100: A Ranking of the Most Influential Persons in History is a 1978 book by Michael H. Hart, reprinted in 1992 with revisions. It is a ranking of the 100 people who, according to Hart, most influenced human history.^[1]

The first person on Hart's list is the Prophet of Islam Muhammad.^[2] Hart asserted that Muhammad was "supremely successful" in both the religious and secular realms. He also believed that Muhammad's role in the development of Islam was far more influential than Jesus' collaboration in the development of Christianity. He attributes the development of Christianity to St. Paul, who played a pivotal role in its dissemination."^[3]

The 1992 revisions included the demotion of figures associated with Communism, such as Vladimir Lenin and Mao Zedong, and the introduction of Mikhail Gorbachev. Hart took sides in the Shakespearean authorship issue and substituted Edward de Vere, 17th Earl of Oxford for William Shakespeare. Hart also substituted Niels Bohr and Henri Becquerel with Ernest Rutherford, thus correcting an error in the first edition. Henry Ford was also promoted from the "Honorary Mentions" list, replacing Pablo Picasso. Finally, some of the rankings were re-ordered, although no one listed in the top ten changed position.

Hart wrote another book in 1999, entitled A View from the Year 3000,^[4] voiced in the perspective of a person from that future year and ranking the most influential people in history. Roughly half of those entries are fictional people from 2000–3000, but the remainder are actual people. These were taken mostly from the 1992 edition, with some re-ranking of order.

Hart's Top 10 (from the 1992 edition)[link]

Rank	Name	Time Frame	Image	Occupation	Influence
1	Muhammad	c. 570–632		Secular and religious leader	The central human figure of Islam, regarded by Muslims as a prophet of God and the last messenger. Active as a social reformer, diplomat, merchant, philosopher, orator, legislator, military leader, humanitarian, philanthropist.
2	Isaac Newton	1643–1727		Scientist	English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian. His law of universal gravitation and three laws of motion laid the groundwork for classical mechanics.
3	Jesus Christ	7–2 BC – 26–36 AD		Spiritual leader	The central figure of Christianity, revered by Christians as the Son of God and the incarnation of God.
4	Buddha	563–483 BC		Spiritual leader	Spiritual teacher and philosopher from ancient India. Founder of Buddhism and is also considered an Gautama Buddha in Hinduism.
5	Confucius	551–479 BC		Philosopher	Chinese thinker and social philosopher, whose teachings and philosophy have deeply influenced Chinese, Korean, Japanese, Vietnamese and Indonesian thought and life. Founded Confucianism, and influenced Neo-Confucianism and New Confucianism.
6	St. Paul	5–67 AD		Christian apostle	One of the most notable of early Christian missionaries, credited with proselytizing and spreading Christianity outside of Palestine (mainly to the Romans) and author of numerous letters of the New Testament of the Bible.
7	Cài Lún	50–121 AD		Political official in imperial China	Widely regarded as the inventor of paper and the papermaking process.
8	Johannes Gutenberg	1398–1468		Inventor	German printer who invented the mechanical printing press.
9	Christopher Columbus	1451–1506	70px	Explorer	Italian navigator, colonizer and explorer whose voyages led to general European awareness of the American continents.
10	Albert Einstein	1879–1955		Scientist	German theoretical physicist, best known for his theory of relativity and specifically mass–energy equivalence, expressed by the equation E = mc2.

See also[link]

• Time 100

References[link]

1. ^ Michael H. Hart The 100: A Ranking of the Most Influential Persons in History. first published in 1978, reprinted with minor revisions 1992. ISBN 978-0-8065-1068-2
2. ^ The 100: A Ranking of the Most Influential Persons in History^{[dead link]}
3. ^ Michael H. Hart, "The 100: A Ranking of the Most Influential Persons in History", Citadel Publishing, 2000, ISBN 978-0-8065-1350-8
4. ^ Michael H. Hart. A view from the year 3000: a ranking of the 100 most influential persons of all time; first published in 1999

External links[link]

• Religious Affiliation of History's 100 Most Influential People