The first load of passengers queuing for the Bennie Railplane in Glasgow; the inventor George Bennie is third in the queue. The streamlined cars are self propelled, driven by air screws in front and behind, and hang from a steel girder. (Photo by J. A. Hampton/Topical Press Agency/Getty Images). 4th July 1930

Sam Warren climbs in to a prototype combat vehicle during the PrepperCon expo Friday, April 24, 2015, in Sandy, Utah. Hundreds of survivalists and “preppers” are gathering in the Salt Lake City suburb of Sandy for the first annual PrepperCon, featuring demonstrations of underground bunkers, food storage, and armored vehicles. (Photo by Rick Bowmer/AP Photo)

An Afghan man is carried out of a hospital after receiving treatment following a suicide truck bomb attack in Kabul, Afghanistan August 7, 2015. The bombings were the first in Kabul since Mullah Akhtar Mansour took charge of the Taliban last week, and followed a rare truck bomb attack in an eastern province on Thursday. (Photo by Omar Sobhani/Reuters)

Dancers audition for a post as cheerleaders of the Miami Dolphins, in Rio de Janeiro, Brazil, Thursday, March 3, 2016. Brazilian dancers audition in the first international cheerleader recruitment for the Miami Dolphins in Rio de Janeiro. The Dolphins will also hold auditions in Colombia, Argentina, Mexico and South of Florida. (Photo by Felipe Dana/AP Photo)

A woman directs traffic in the pouring rain in Pyongyang, North Korea on May 3, 2016. The city is preparing for the Workers' Party Congress starting on May 6th. It will be the first time since 1980 that the ruling party has convened. (Photo by Linda Davidson/The Washington Post)

A hunter holds a shot female pheasant next to his dog “Lola”, a Deutsch female Kurzhaar, during the first day of the Italy hunting season in Castell'Azzara, Tuscany, central Italy, September 20, 2015. The number of hunters in Italy has been decreasing, from 1,701,853 in 1980 to 751.876 in 2007, with a percentage reduction of 55.8%, according to the latest available numbers from the national statistics bureau ISTAT. (Photo by Max Rossi/Reuters)

Indian folk dancers display ornaments during a break while participating in the first night of Navratri in Gandhinagar, some 30 km from Ahmedabad, on October 13, 2015. Navratri festivities, or Dance Festival of Nine Nights, takes place between October 13-21. (Photo by Sam Panthaky/AFP Photo)

An indigenous woman participates in a parade called "International Indigenous Beauty" during the first World Games for Indigenous Peoples in Palmas, Brazil, October 24, 2015. Billed as the indigenous Olympics, the games are expected to attract nearly 2,000 athletes from dozens of Brazilian ethnicities, as well as from such far-flung nations as Ethiopia and New Zealand. (Photo by Ueslei Marcelino/Reuters)