Princess Diana relaxes on the sand during a visit to the beach on the Caribbean Island of Nevis January 4, 1993. (Photo by Mark Cardwell/Reuters)

N.C. Dezendorf, wife of the general manager of the Electro-Motive division of General Motors, christens the new lightweight “Aerotrain” at the company's locomotive works in La Grange, Ill. on August 22, 1955. (Photo by Edward Kitch/AP Photo)

New Orleans police officers try to keep their heads down as they move in on a Black Panther headquarters during an exchange of gunfire in New Orleans on September 15, 1970. The shootout occurred as police moved in to make arrests on Tuesday morning following a series of incidents. (Photo by Jack Thornell/AP Photo)

Soldiers and firefighters carry the body of Chilean President Salvador Allende, wrapped in a Bolivian poncho, out of La Moneda presidential palace after it was bombed during a coup by Gen. Augusto Pinochet in Santiago, Chile, September 11, 1973. (Phoot by El Mercurio/AP Photo)

A female motorcycle cop directs traffic wearing crash helmet, Haywarket Square, Boston, Massachusetts, 1979. (Photo by Spencer Grant/Getty Images)

Members of the Hitler Youth who are trained to report airstrikes repaining their bicycles. Published by: “Die Sirene”. 1942. (Photo by Herbert Hoffmann/Ullstein Bild via Getty Images)

The Burney, a new streamlined car on the London streets, designed by Sir Denniston Burney who was responsible for the design of the R100 (R 100) airship. The engine is in the rear. (Photo by Topical Press Agency/Getty Images). 15th September 1930

Children feeding the birds in this Victorian Christmas greetings card. (Photo by Hulton Archive/Getty Images). Circa 1885