How did spectacles originated?

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Around 1000 AD the first vision aid was invented called a reading stone, which was a glass sphere that was laid on top of the material to be read the magnified the letter. Around 1284 in Italy Salvino D'Armate is creadited with inventing the first wearable eye glasses.

The ingenious American inventor Benjamin Franklin invented bifocal spectacles in 1784. He was getting old and was having troubles seeing objects both close up and at a distance. He grew so tired of switching two different pairs of spectacles so he devised a way to have both types of lenses fit into a single frame. The distance lens was placed at the top and the up close lens was placed at the bottom. Bifocal spectacles are made this way even today.

The oldest known lens was founded in the ruins of ancient Nineveh and was made of polished rock crystal, 4 cms in diameter.

Around the year 1752 eyeglass designer James Ayscough introduced his spectacles with double-hinged side pieces. The lenses were made of tinted glass as well as clear. Ayscough felt that white glass created an offensive glaring light that was bad to the eyes. He advised the use of green and blue glasses. Ayscough glasses were the first sunglasses but they were not made to shield the eyes from the sun they corrected for vision problems.

Edwin.H.Land invented a cellophane like polarizing filter the first modern filters to polarize light. Polarizing celluloid became the critical element in polarizing sunglasses lenses; it is a process that reduces light.

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