Three workers demonstrating the different types of gas masks used in mine rescue work. (Photo by Fox Photos/Getty Images). December 1925

A three wheeled “cabin” scooter manufactured by German aircraft engineers Messerschmitt & Co at factories in Regensburg. (Photo by Hans Enzwieser/BIPs/Getty Images). 1955

Ginger Stanley performs a grand jete during her solo underwater ballet at Silver Springs, Florida. (Photo by Bruce Mozert/Three Lions/Getty Images). Circa 1956

Racing fans soak up the sunshine and dress to impress during Ladies Day at the Aintree Grand National meeting on April 8, 2011 in Aintree, England. Friday is traditionally Ladies day at the three-day meeting of the world famous Grand National, where fashion is as important as the racing.

French artist Olivier Grossetête used three enormous helium balloons to float a rope bridge over a lake in Tatton Park, a historic estate in north-west England.

Magbola Alhadi, 20, and her three children pose for a portrait in Jamam refugee camp in Maban County, South Sudan on August 11th, 2012. Magboola and her family weathered aerial bombing raids for several months, but decided it was time to leave their village of Bofe the night that soldiers arrived and opened fire. With her three children, she travelled for 12 days from Bofe to the town of El Fudj, on the South Sudanese border. The most important thing that Magboola was able to bring with her is the saucepan she holds in this photograph. It wasn't the largest pot that she had in Bofe, but it was small enough she could travel with it, yet big enough to cook sorghum for herself and her three daughters (from left: Aduna Omar, 6, Halima Omar, 4, and Arfa Omar, 2) during their journey. (Photo by Brian Sokol/Panos Pictures)

A topless Femen activist jumps on the car carrying former IMF chief Dominique Strauss-Kahn (not seen) as he arrives for his trial in Lille, northern France, on February 10, 2015. Three topless women from the protest group Femen jumped on the car of Dominique Strauss-Kahn as the former IMF chief arrived to testify at his trial for “aggravated pimping”. With slogans scrawled on their half-naked bodies and hurling insults at the car, the three protesters were quickly rounded up by police as the car entered an underground parking area. (Photo by Denis Charlet/AFP Photo)

Israeli soldiers pray at dawn as the conflict between Palestine and Gaza enters its seventh day on November 20, 2012 on Israel's border with the Gaza Strip. Hamas militants and Israel are continuing talks aimed at a ceasefire as the death toll in Gaza reaches more than 100 and also three Israelis killed by rockets fired by Palestinian militants. (Photo by Christopher Furlong)