barn

barn, abbr. b, in physics, unit of nuclear cross section, i.e., the effective target presented by a nucleus for collisions leading to nuclear reactions; it is equal to 10^-24 square centimeters. The barn is approximately the size of the geometric cross section of an atomic nucleus; the term was coined because an effective cross section that large would present a target "as big as a barn," i.e., an easy target for nuclear bombardment. In practice, effective cross sections of nuclei for many reactions are measured in millibarns (10^-3 barn) because, for most interactions, only a small fraction of collisions cause reactions.

Any of several species of nocturnal birds of prey (genus Tyto), sometimes called monkey-faced owls because of their heart-shaped facial disk and absence of ear tufts. Barn owls are about 12–16 in. (30–40 cm) long, white to gray or yellowish to brownish orange. Their dark eyes are smaller than those of other owls. They hunt mainly small rodents, often on cultivated land, and nest in hollow trees, buildings, towers, and old hawk nests. The common barn owl is found worldwide except in Antarctica and Micronesia. Other species occur only in the Old World.

Learn more about barn owl with a free trial on Britannica.com.

Farm building used for sheltering animals, their feed and other supplies, farm machinery, and farm products. Barns are named according to their purpose (e.g., hog barns, dairy barns, tobacco barns, and tractor barns). The principal type in the U.S. is the general-purpose barn, used for housing livestock and for storing hay and grain. Most North American and European farms have one or more barns. They usually consist of two stories, though one-story barns gained in popularity in the late 20th century.

Learn more about barn with a free trial on Britannica.com.

A barn is an agricultural building used for storage and as a covered workplace. It may sometimes be used to house animals or to store farming vehicles and equipment. Barns are most commonly found on a farm or former farm.

Construction

Older barns were usually built from lumber sawn from timber on the farm, although stone barns were sometimes built in New England, U.S.A., and other areas where stone was a cheaper building material. Modern barns are more typically steel buildings. Prior to the 1900s, most barns were timber framed (also known as post and beam) forming very strong structures to withstand storms and heavy loads of animal feed. From about 1900 to 1940, many large dairy barns were built in northern USA. These commonly have gambrel, or hip roofs to maximize the size of the hayloft above the dairy roof, and have become associated in the popular image of a dairy farm. The barns that were common to the wheatbelt held large numbers of pulling horses such as Clydesdales or Percherons. These large wooden barns, especially when filled with hay, could make spectacular fires that were usually total losses for the farmers. With the advent of balers it became possible to store hay and straw outdoors in stacks surrounded by a plowed fireguard. Many barns in the northern United States are painted red with a white trim. One possible reason for this is that ferric oxide, which is used to create red paint, was the cheapest and most readily available chemical for farmers in New England and nearby areas. Another possible reason is that ferric oxide acts a preservative and so painting a barn with it would help to protect the structure.

With the popularity of tractors following World War II many barns were taken down or replaced with modern Quonset huts made of plywood or galvanized steel. Beef ranches and dairies began building smaller loftless barns often of Quonset huts or of steel walls on a treated wood frame (old telephone or power poles). By the 1960s it was found that cattle receive sufficient shelter from trees or wind fences (usually wooden slabs 20% open).

Uses

In older style barns, the upper area was used to store hay and sometimes grain. This is called the mow (rhymes with cow) or the hayloft. A large door at the top of the ends of the barn could be opened up so that hay could be put in the loft. The hay was hoisted into the barn by a system containing pulleys and a trolley that ran along a track attached to the top ridge of the barn. Trap doors in the floor allowed animal feed to be dropped into the mangers for the animals.

In New England, it is common to find barns attached to the main farmhouse (connected farm architecture), allowing for chores to be done while sheltering the worker from the weather.

In the middle of the twentieth century, the large broad roof of barns were sometimes painted with slogans in the United States. Most common of these were the 900 barns painted with ads for Rock City.

Barn Features

A farm often has pens of varying shapes and sizes used to shelter large and small animals. The pens used to shelter large animals are called stalls and are usually located on the lower floor. Other common areas, or features, of a typical barn include:

• a tack room (where bridles, saddles, etc. are kept), often set up as a breakroom
• a feed room, where animal feed is stored - not typically part of a modern barn where feed bales are piled in a stackyard
• a drive bay, a wide corridor for animals or machinery
• a silo where fermented grain or hay (called ensilage or haylage) is stored.
• a milkhouse for dairy barns; an attached structure where the milk is collected and stored prior to shipment
• a grain (soy, corn, etc) bin for dairy barns, found in the mow and usually made of wood with a chute to the ground floor providing access to the grain, making it easier to feed the cows.
• modern barns often contain an indoor corral with a squeeze chute for providing veterinary treatment to sick animals.

Derivatives

The physics unit "barn", which is a unit of exceedingly small area, was named for the "barn", given the surprisingly large size of this property for a particular element.

Barn idioms

• "He couldn't hit the broad side of a barn" is a popular expression for a person having poor aim when throwing an object or when shooting at something.
• To "lock the barn door after the horse is gone" implies that one is trying fix a problem after it is too late.
• "Were you raised in a barn?" is an accusation used differently in various parts of the English-speaking world, but most common as a reprimand when someone exhibits poor manners by either using ill-mannered language (particularly if related to manure), or leaving doors open.
• "Your barn door is open" is used as a euphemism to remind someone to zip the fly of their trousers.

See also

• Stable
• Barn conversion
• Bank barn
• Barn raising
• Barnyard
• Carriage house
• Dutch barn
• Farmhouse (building)
• Functionally classified barn
• Round barn
• barn (unit)
• Tobacco barn

External links

• Dairy Barn History
• www.thebarnjournal.org