The book “Elektroschutz in 132 Bildern” (Electrical Protection in 132 Pictures) was published in Vienna in the early 1900s by a Viennese physician named Stefan Jellinek (1878-1968, a founder of the Electro-Pathological Museum). The pictures are nice and direct and unambiguous; they teach, graphically, that the surest way to kill yourself with electricity is to form a complete path from source (usually the bright red arrow) to ground (the screened back, pink arrow). Arrowheads provide the path for current flow. (Photo by The Vienna Technical Museum)

A visitor to ''The Cult of Beauty: The Aesthetic Movement 1860-1900'' exhibition at The V&A Museum looks at sculptures by Thornycroft (L) and Watts on March 30, 2011 in London, England. This exhibition brings together for the first time many masterpieces in painting, sculpture, design and furniture as well as fashion and literature and runs from April 2nd to July 17th 2011.

Their Royal Highnesses Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge kiss on the balcony at Buckingham Palace on April 29, 2011 in London, England. The marriage of the second in line to the British throne was led by the Archbishop of Canterbury and was attended by 1900 guests, including foreign Royal family members and heads of state. Thousands of well-wishers from around the world have also flocked to London to witness the spectacle and pageantry of the Royal Wedding. (Photo by Peter Macdiarmid/Getty Images)

Senator Barack Obama (D-IL) (R) stands in front of Senator Hillary Clinton (D-NY) as they arrive for U.S. President George W. Bush's annual State of the Union speech to a joint session of Congress at the U.S. Capitol in Washington in this January 23, 2007 file photo. Hillary Clinton announced her second run for the presidency on April 12, 2015 starting her campaign as the Democrats' best hope of fending off a crowded field of lesser-known Republican rivals and retaining the White House. (Photo by Larry Downing/Reuters)

A newly born Mexican gray wolf cub, an endangered native species, is seen at its enclosure at the Museo del Desierto in Saltillo, Mexico, July 19, 2016. Though once held in high regard in Pre-Columbian Mexico, it is the most endangered gray wolf in North America, having been extirpated in the wild during the mid-1900s through a combination of hunting, trapping, poisoning and digging pups from dens. (Photo by Daniel Becerril/Reuters)

Lucha libre is Mexico’s version of what in the United States refer to as pro wrestling. Its dates to 1863, when a Mexican wrestler named Enrique Ugartechea developed a form of “freestyle” wrestling that was based on Greco-Roman wrestling. Lucha libre began to soar in popularity in Mexico after two Italian businessmen started promoting fights in the early 1900s. It has since become popular around the globe. Here: Juliza meets with colleagues at her home. (Photo by Diana Bagnoli/The Washington Post)

General view of the screens in Hyde Park to showing the Royal Wedding on April 29, 2011 in London, England. The marriage of Prince William, the second in line to the British throne, to Catherine Middleton is being held in London today. The Archbishop of Canterbury conducted the service which was attended by 1900 guests, including foreign Royal family members and heads of state. Thousands of well-wishers from around the world have also flocked to London to witness the spectacle and pageantry of the Royal Wedding and street parties are being held throughout the UK. (Photo by Tom Dulat/Getty Images)