REUTLINGEN, GERMANY - NOVEMBER 17: Students hang out finished parchment leather at the LGR (Lederinstitut Gerberschule Reutlingen) tannery school on November 17, 2010 in Reutlingen, Germany. Even in early antiquity and up their hair or dried goat and sheep skins were used as material for documents. In the small Asian city Pergamon these skins were processed in large quantities for this purpose, so they formed the main trading arm of the city, of which the name is parchment is derived. In medieval times, reached the parchment is of great importance, it was such as France's production under the supervision of the University of Paris. Even now, important documents, placed on their unlimited shelf life as possible large value (eg diplomas, addresses, memory, writings, documents for primary and keystones) written on parchment...

South Korean teenagers participate in a warfare exercise as part of the Special Warfare Command's training course at a military base on August 4, 2011 in Seoul, South Korea. About 1,000 civilian volunteers including middle and high school students participated in the special force's four-day training programme to develop their spiritual and physical strength. (Photo by Chung Sung-Jun/Getty Images)

Participants learn how to survive in the wild, including tips on how to make it through a zombie invastion at a “Zombie First Responder” course March 11, 2012 in Sandy, Oregon. In an intensive 2-day curriculum participants train in everything from wilderness and urban survival, nerf or nerd weaponry, stealth and evasion, and proper zombie “disposal”. (Photo by Natalie Behring/Getty Images)

Bonhams employee Craig Binns polishes a, 1903 two seater moter car, the world oldest surviving Vauxhall, on November 1, 2012 in London, England. The Car is part of a Veteran Car Sale at Bonhams and is valued at around 80,000 pounds (Photo by Bethany Clarke)

Number 10. BELL H-13 SIOUX was a two-bladed, single engine, light helicopter built by Bell Helicopter. Westland Aircraft manufactured the Sioux under license for the British military as the Sioux AH.1 and HT. In 1947, the United States Air Force ordered the improved Bell Model 47A. Most were designated YR-13 and three winterized versions were designated YR-13A. The United States Army first ordered Bell 47s in 1948 under the designation H-13. These would later receive the name Sioux. The Bell-built H-13 B is seen airborne in this April 29, 1951 photo. The helicopter is equipped with a 173 horsepower engine, cruises at 85 miles per hour, climbs 900 feet in a minute and has a service ceiling of 11,500 feet. (Photo by AP Photo)

Aiden Haas, left, and Lilli Alcala pose after being crowned Mud King and Mud Queen at the 29th annual Mud Day, Tuesday, July 12, 2016 in Westland, Mich. The event, open to children 12 and younger, was at the Hines Park-Nankin Mills Area west of Detroit. Children 12 and younger were able to slosh around in the pit while participating in mud limbo, wheelbarrow races and other free activities. (Photo by Carlos Osorio/AP Photo)

Mud Day Queen Riley Tulgetske, left, embraces Mud Day King Phoenix Crowder during Mud Day at the Nankin Mills Park, Tuesday, July 9, 2019, in Westland, Mich. The annual day is for kids 12 years old and younger. While parents might be welcome, this isn't an event meant for teens or adults. It's all about the kids having some good, unclean fun during their summer break and is sponsored by the Wayne County Parks. (Photo by Carlos Osorio/AP Photo)

Sydney Truba, 11, of Melvindale, Michigan lies in a giant lake of mud during Wayne County's 2011 Mud Day event at Nankin Mills Park July 12, 2011 in Westland, Michigan. The annual event consists of 20,000 gallons of water mixed with 200 tons of topsoil. (Photo by Bill Pugliano/Getty Images)