The contact lens, a thin plastic lens worn between the eye and eyelid, usually serves the same general corrective purpose as conventional glasses, but may be worn for cosmetic or therapeutic purposes as well. Leonardo da Vinci is frequently credited with having introduced the general principle of contact lenses, but it was A.E. Fick, a Swiss physician, who made the first, albeit uncomfortable, contact lens in 1887. According to estimates, how many people use contact lenses worldwide?
Back in the day
Viewed by many as the result of a period of factional infighting and religious hysteria, the witch trials of Puritanical Salem Village, Massachusetts led to the executions of 20 people (14 women, 6 men) and the imprisonment of between 175 and 200 people. Even after the witch trials ended, people who had previously been found not guilty of witchcraft were not released until they paid their jailers' fees. What is "spectral evidence," and how did it play a role in the witch trials?
Born on a day like today
According to the 9/11 Commission Report, Mohammed was the principle architect of the 9/11 attacks. He is thought to have been born in Pakistan, and spent some of his formative years in Kuwait, joining the Muslim Brotherhood at age 16. He studied in the US and in the 1980s fought for the CIA against the Soviet invasion of Afghanistan. It is thought that his anti-American terrorist operations began in the early 1990s, culminating in his membership in Al-Qaeda, where he was put in charge of what?