Russian soldiers write home while serving on the Eastern Front during World War I, circa 1915. (Photo by Hulton Archive/Getty Images)

A member of the German wireless police picks up signals on the radio equipment he carries on his back, while his colleague takes notes. (Photo by General Photographic Agency/Getty Images). Circa 1925

A Mark IV tank, part of the parade at the Lord Mayor's Show in London. (Photo by Topical Press Agency/Getty Images). November 1917

A workman takes a siesta on a girder during the building of Radio City, the city of New York spread out below. (Photo by General Photographic Agency/Getty Images). Circa 1933

Egyptian bootblacks cleaning a European's shoes in Cairo. (Photo by Hulton Archive/Getty Images). Circa 1870

The Verreauxs Sifaka, otherwise known as Dancing Sifaka, who was caught strutting its stuff in Madagascar, has definitely learnt a lesson or two from King Julian – from the 2005 film “Madagascar”. Raising both of its arms and lunging from side to side, this lemur definitely likes to move it, move it. (Photo by Shannon Wild/Caters News Agency)

A Mercedes-Benz car is pictured in a production line at the plant of German carmaker Mercedes-Benz in Bremen, Germany January 24, 2017. (Photo by Fabian Bimmer/Reuters)

A protester uses molotov cocktails against riot police during May Day protests on May 1, 2010 in Athens, Greece. (Photo by Milos Bicanski /Getty Images)