Benjamin franklin inventions
What purpose do bifocal spectacles serve.
How have bifocal spectacles impacted society today
Bifocals
Eyeglasses with two distinct optical powers
For the bifocal tensor, see Fundamental matrix (computer vision).
Bifocals are eyeglasses with two distinct optical powers correcting vision at both long and short distances.
Bifocals are commonly prescribed to people with presbyopia who also require a correction for myopia, hyperopia, and/or astigmatism.
History
Benjamin Franklin is generally credited with the invention of bifocals.
He decided to saw his lenses in half so he could read the lips of speakers of French at court, the only way he could understand them.[1] Historians have produced some evidence to suggest that others may have come before him in the invention; however, a correspondence between George Whatley and John Fenno, editor of the Gazette of the United States, suggested that Franklin had indeed invented bifocals, and perhaps 50 years earlier than had been originally thought.[2] On the contrary, the College of Optometrists con