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Man with glasses. A woman with glasses. Glasses, also known as eyeglasses or spectacles, are vision eyewear with clear or tinted lenses mounted in a frame that holds them in front of a person's eyes, typically utilizing a bridge over the nose and hinged arms, known as temples or temple pieces, that rest over the ears for support.
Often used by monks to assist in illuminating manuscripts, these were primitive plano-convex lenses, initially made by cutting a glass sphere in half. As the stones were experimented with, it was slowly understood that shallower lenses magnified more effectively. Around 1286, possibly in Pisa, Italy, the first pair of eyeglasses was made ...
A very important advance in glass manufacture was the technique of adding lead oxide to the molten glass; this improved the appearance of the glass and made it easier to melt using sea-coal as a furnace fuel. This technique also increased the "working period" of the glass, making it easier to manipulate.
Red-tinted lenses were considered effective in reducing internecine pecking because they disguise the color of blood. [7] As summed up in a 1953 article in Indiana's National Road Traveler newspaper, "The deep rose-colored plastic lenses make it impossible for the cannibal [chicken] to see blood on the other chickens, although permitting it to see the grain on the ground."
In the 1790s, the O'Hara and Craig glass works was the first glass works in Pittsburgh, and this works was another early user of coal as a fuel for its furnaces. [67] By 1800, it is thought that roughly ten glass works were operating in the United States. [68] Challenges for American glass works revolved around labor, raw materials, and imports.
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In 1888, Adolf Gaston Eugen Fick was the first to successfully fit contact lenses, which were made from blown glass. Although Louis J. Girard invented a scleral contact lens in 1887, [16] it was German ophthalmologist Adolf Gaston Eugen Fick who in 1888 fabricated the first successful afocal scleral contact lens. [17]