Barbed wire
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Image:Barbed wire, Melbourne Museum.jpg
Barbed wire is a type of fencing wire constructed with sharp edges or points arranged at intervals along the strand(s). It is used to construct inexpensive fences. A person or animal trying to pass through a barbed-wire fence will suffer discomfort and possibly injury. Barbed-wire fencing requires only fenceposts, wire and fixing devices such as staples. It is simple to construct and quick to erect by a skilled, or even an unskilled fencer.
The most successful barbed wire was patented by Joseph F. Glidden of DeKalb, Illinois in 1874. It was an improvement on earlier less successful pointed wire products such as that invented in 1865 by Louis Jannin of France.
Barbed wire was the first wire technology capable of restraining cattle. Wire fences were cheaper to erect than their alternatives and when they became widely available in the late 19th century in the United States they made it affordable to fence much bigger areas than before. They made intensive animal husbandry practical on a much larger scale.
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In the American Southwest
Image:Barbed wire.jpg John Warne Gates demonstrated barbed-wire in Military Plaza, San Antonio, Texas in 1876. The demonstration showing cattle restrained by the new kind of fencing was followed immediately by invitations to the Menger Hotel to place orders. Within 25 years, nearly all of the open range had been fenced in under private ownership. In 1875, 270 tons of barbed wire had been manufactured, and by 1901 production had increased to 135,000 tons. By that time Gate's American Steel and Wire Company held a monopoly in the wire business.
In the American Southwest barbed-wire fencing led to disputes known as the range wars between free-range ranchers and farmers in the late 19th century. These were similar to the disputes which resulted from enclosure laws in England in the early 18th century. These disputes were decisively settled in favor of the farmers, and heavy penalities were instituted for cutting the wire in a barbed-wire fence. Within 25 years, nearly all of the open range had been fenced in under private ownership. For this reason, some historians have dated the end of the Old West era of American history to the invention and subsequent proliferation of barbed wire.
Barbed-wire fences remain the standard fencing technology for enclosing cattle in most regions of the US, but not all countries. The wire is aligned under tension between heavy, braced, fence posts (strainer posts) and then held at the correct height by being attached to wooden posts and battens, or steel star posts. The gaps between star posts vary depending on terrain—on short fences in hilly country they may be placed as closely as every 3 yards, whereas in flat terrain with long spans and relatively few stock they may be spaced out up to 30 to 50 yards. Wooden posts are normally spaced at 2 rods (10 metres) in any case with 4 or 5 batterns in between.
Agricultural fencing
Image:Barbedwire3.jpgBarbed wire for agricultural fencing is typically available in two varieties—"soft" or mild-steel wire and "high tensile". Both types are galvanised for long life. High-tensile wire is made with thinner but higher-strength steel. Its greater strength make fences longer-lasting because cattle cannot stretch and loosen it. It copes with the expansions and contractions caused by heat and animal pressure by stretching and relaxing within wider elastic limits. It also supports longer spans, but because of its "springy" nature it is less easy, and somewhat dangerous, for inexperienced fencers. Soft wire is much easier to work but is less durable and only suitable for short spans.
In high soil-fertility areas where dairy cattle are used in great numbers 5- or 7-wire fences are common as the main boundary and internal dividing fences. On sheep farms 7-wire fences are common with the second (from bottom) to fifth wire being plain wire. In New Zealand wire fences have to be easy to get through by dogs because they are the main means of controlling and driving animals on farms.
Human-proof fencing
Most barbed-wire fences, while sufficient to discourage cattle, are passable by humans who can simply climb over the fence—or through the fence by stretching the gaps between the wires using non-barbed sections of the wire as handholds. To prevent humans crossing, many prisons and other high-security installations construct fences with razor wire, a variant which instead of occasional barbs features near-continuous cutting surfaces sufficient to severely injure anyone who climbs on or over it. A more commonly seen alternative is placing a few strands of barbed wire at the top of a chain link fence. The limited mobility allowed to someone already climbing a fence makes passing conventional barbed wire all the more difficult.
Barbed wire is also used in war. Much of the artillery bombardment on the Western Front in World War I was aimed at cutting the barbed wire that was a major feature of trench warfare. The wire was not designed to stop the passage of men, just to impede them long enough to kill them with machine guns.
Injuries caused by barbed wire
Unrestrained violence against barbed wire will always result in moderate to severe injuries to the skin and, depending on body area and barbed wire configuration, possibly to the underlying tissue. Humans manage to not injure themselves too much when dealing with barbed wire as long as they exert a high degree of caution. Restriction of movement, appropriate clothing, and slowing down when close to barbed wire seem to be the key in reducing the extent of injury.
Injuries caused by barbed wire are typically seen in horses, bats or birds. Horses panic easily, and once they get caught in barbed wire, large patches of skin may be torn off, sometimes exposing the underlying bone. At best, such injuries may heal, but they may cause disability or death (particularly due to secondary infection). Birds or bats may not be able to perceive thin strands of barbed wire and suffer impalement or lacerating injuries.
Grazing animals with slow movements which will back off at the first notion of pain — sheep, cows — will not generally suffer the severe injuries often seen in other animals.
Barbed wire has been reported as a tool to torture people. There are some indications as to the precise extent of injuries. Other reports include deaths as possible consequence of barbed wire abuse, and even though full details about further investigations are missing, one has to assume that deep lacerations caused by barbed wire may also cause severe bleeding.
Installation of barbed wire
Image:BarbedWirePatentGlidden.jpgThe most important and most time-consuming part of a barbed wire fence is constructing the corner post and the bracing assembly. A barbed wire fence is under tremendous tension, often up to half a ton, and so the corner post's sole function is to resist the tension for all fence spans connected to it. The bracing, in turn, keeps the corner post perfectly vertical and prevents slack from developing in the fence.
Brace posts are placed in-line about 8 feet from the corner post. A horizontal compression brace connects the top of the two posts, and a diagonal wire connects the top of the brace post to the bottom of the corner post. This diagonal wire prevents the brace post from leaning, which in turn allows the horizontal brace to prevent the corner post from leaning into the brace post. A second set of brace posts (forming a double brace) is used whenever the barbed wire span exceeds 200 feet (60 m).
When the barbed wire span exceeds 650 ft (200 m), a braced line assembly is added in-line. This has the function of a corner post and brace assembly but handles tension from opposite sides. It uses diagonal brace wire that connects the tops to the bottoms of all adjacent posts.
Line posts are installed along the span of the fence at intervals of 8 to 50 ft (2.5 m to 15 m). An interval of 16 ft (5 m) is most common. Heavy livestock and crowded pasture demands the smaller spacing. The sole function of a line post is not to take up slack but to keep the barbed wire strands spaced equally and up off the ground.
Once these posts and bracing have been erected, the wire is wrapped around one corner post, held with simple fence staples, and then reeled out along the span of the fence. It is then wrapped around the opposite corner post, pulled tightly by hand, and nailed with more fence staples. Then it is attached to all of the line posts with fencing staples driven in partially to allow stretching of the barbed wire line.
It is installed from the top down.
There are several ways to anchor the wire to a corner post:
- Hand-knotting. The wire is wrapped around the corner post and knotted by hand.
- Crimp sleeves. The wire is wrapped around the corner post and bound to the incoming wire using metal sleeves.
- Wire vise. The wire is passed through a hole drilled into the corner post and is anchored on the far side.
- Wire wrap. The wire is wrapped around the corner post and wrapped onto a special, gritted helical wire which also wraps around the incoming wire; friction holds it in place.
- Gripple. The wire is wrapped around the corner post and gripped by a vise which also attaches to the incoming wire.
Barbed wire for agriculture use is typically double-strand 12½-gauge, zinc-coated (galvanized) steel and comes in rolls of 1320 ft (402 m) length. Barbed wire is usually placed on the inner (pasture) side of the posts.
Galvanized wire is classified into three categories; Classes I, II, and III. Class I has the thinnest coating and the shortest life expectancy. A wire with Class I coating will start showing general rusting in 8 to 10 years, while the same wire with Class III coating will show rust in 15 to 20 years. Aluminum-coated wire is occasionally used which yields a longer life expectancy.
Corner posts are 6 to 8 inches (15 to 20 cm) in diameter, may consist of treated wood or from durable on-site trees such as osage orange, black locust, red cedar, or red mulberry and are anchored in a concrete base 20 inches (50 cm) square and 42 inches (105 cm) deep. Brace posts are a minimum 4 inches (10 cm) in diameter and are anchored in a concrete base 20 inches (50 cm) square and 24 inches (60 cm) deep. Iron posts, if used, are a minimum 2½ inch (64 mm) in diameter. Bracing wire is typically smooth 9-gauge. Line posts are set to a depth of about 30 inches (75 cm).
During the First World War, screw pickets were used for the installation of wire obstacles; these were metal rods with eyelets for holding strands of wire, and a corkscrew-like end that could literally be screwed into the ground rather than hammered, so that wiring parties could work at night within the vicinity of enemy soldiers and not give away their position by the sound of their hammers.
See also
References
- Henry D. and Frances T. McCallum. The Wire that Fenced the West. Norman: University of Oklahoma Press, 1965. LoC: 65-11234.
- Olivier Razac. Barbed Wire: A Political History, W. W. Norton & Company, 2003, ISBN 1565848128
- Biography of John W. Gates, barbed wire promoter who monopolized the industry with the American Steel and Wire Company, accessed March 29, 2006
External links
Information
- History of the invention of barbed wire
- Development and Rise of Barbed Wire at University of Virginia accessed March 29, 2006
- Glidden's patent for barbed wire accessed March 29, 2006
- Barbed Wire in Texas
- Barbed wire changes life on the American Great Plains
- Interesting snippets and references to barbed wire
- A political history of barbed wire
- The historical plaque outside Menger Hotel in San Antonio erected in 2000, accessed 14 November 2005.
Patents – some of the 570 that have been issued:
- Template:US patent – Henry Jenkins, Pottsville, Pennsylvania, Wire fence – "composed of heavy wire mesh" (1849)
- Template:US patent – J B Reyman, Bloomington, Illinois, Construction of Wire fences – "fastening pickets to wire and picket fences"(1857)
- Template:US patent – Lucien Smith, Kent, Ohio, Wire fence – "rotary spools with projecting spurs" (June 1867)
- Template:US patent – William Hunt, Scott, New York, Improvement in Fences – "sharpened spur wheels" (July 1867)
- Template:US patent – Michael Kelly, New York City (!), Improvement in Fences – "thorny fence" (1868)
- Template:US patent – Joshua Rappleye, Seneca County, New York, Improvement in Constructing Wire fence – tensioner for fence with palings (pickets) (1871)
- Template:US patent – Henry Rose, DeKalb County, Illinois, Improvement in Wire-fences – "strips provided with metal points" (1873)
- Template:US patent – Joseph Glidden, DeKalb, Illinois, Improvement in Wire-fences– twisted fence wires with short spur coiled around one of the strands (1874)
- Template:US patent – Jacob Haish, DeKalb, Illinois, Improvement in Wire-fence Barbs – "single piece of wire bent into the form of the letter S" so that both strands are clasped (1875)cs:Ostnatý drát
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