temperatures or levels of humidity). The European EN 166 standard identifies four levels of ballistic protection. "Increased robustness" (marked S) can withstand a 22 mm steel ball weighing 43 g dropped onto the lens from a height of .38 meters (15 inches). "Low energy impact" (marked F) can withstand a 6mm steel ball weighing 0.86 g and traveling at least 45 m/s at the time of impact. "Medium energy impact" (marked B) must be able to protect from a 6 mm 0.86 g steel ball with an impact velocity of 120 m/s. "High energy impact" (marked A) must be able to protect from a 6 mm 0.86 g steel ball with an impact velocity of 190 m/s. History The history of protective eyewear goes back to 1880, when P. Johnson invented eye protectors. Johnson’s design used two layers of semi-opaque cloth. He had in mind that firemen, furnace-men and others exposed to intense light would use them to reduce the light intensity. They did not provide impact protection. As early as 1885, Arthur T. Fullicks bonded several pieces of glass together. It seems that another Englishman, John Crane Woods, had safety in mind when he patented the idea of bonding sheets of transparent cellulose nitrate, using Canadian balsam, between two sheets of glass. The product was unsuccessful due to expense, poor quality and lack of demand. In 1910, Edouard Benedictus, a French chemist, obtained both French and British patents for the manufacturing of laminated safety glass. He obtained a US patent in 1914. Benedictus used gelatin and other adhesives instead of Canadian balsam in the laminated glass. During World War I, laminated glass was used to make small, round lenses in gas masks and for windshields in military motor vehicles and aircraft. (For a number of recent years, the DuPont chemical company gave a Benedictus Award for the innovative use of laminated glass in architecture.) In the 1940s, manufacturers figured out how to sand and make safety glasses and goggles for welders, construction workers, and the like. In the early 1960s the U.S. government sponsored experiments testing the ballistic performance of various plastics and glass for potential use in eyewear, using tests similar to those required by today’s U.S. military standard. After this time, polycarbonate became the standard material used for ballistic eyewear. Investigations since this early work have included examining the effects of manufacturing and layering techniques on the