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en.wikipedia.org/wiki/Bifocals

Bifocals are eyeglasses with two distinct optical powers. Bifocals are commonly prescribed to people with presbyopia who also require a correction for myopia, hyperopia, and/or astigmatism. Contents. [hide]. 1 History; 2 Problems; 3 Future; 4 Bifocals in the animal world; 5 References; 6 Sources; 7 External links. History[ edit].

www.ushistory.org/franklin/science

Benjamin Franklin's inventions, innovations and discoveries including the kite experiment, Franklin stove, bifocals, armonica and more.

www.ushistory.org/franklin/science/bifocals.htm

Bifocals are eyeglasses with an upper and lower half, the upper for distance, and the lower for reading. Bifocals are commonly prescribed to people with presbyopia, a condition that Franklin suffered. Franklin wrote, in August 1784 to his friend George Whatley, that he was "happy in the invention of double spectacles, which ...

factmyth.com/factoids/benjamin-franklin-invented-bifocals

Oct 29, 2015 ... Benjamin Franklin is credited with inventing bifocals, although evidence suggests he may have been simply an early adopter of the split-bifocal lens. ... was wearing them (presumably for years), but it is rather odd that he did not write more about or try to patent the bifocal if he had actually felt he invented it.

www.pbs.org/benfranklin/l3_inquiring_little.html

Of the numerous inventions Franklin created, he did not patent a single one. Franklin ... Swim fins: Ben Franklin loved the water. Growing up in ... Bifocal glasses: Anyone who has had to switch back and forth between reading glasses and distance glasses knows why Franklin invented his "double spectacles." Franklin had ...

www.fi.edu/benjamin-franklin/inventions

Learn all about Benjamin Franklin and some of his greatest inventions such as the Bifocals, the lightning rod, the glass armonica and more! ... An avid swimmer, Franklin was just 11 years old when he invented swimming fins—two oval pieces of wood that, when grasped in the hands, provided extra thrust through the water.

www.fi.edu/benjamin-franklin-faq

Benjamin Franklin's father wanted Ben to become a preacher, so he sent him to grammar school when he was eight years old. After less than a ... What did Benjamin Franklin want to be when he grew up? From his ... So he cut the lenses from both pairs in half, then put half of each lens in a single frame, inventing bifocals.

www.reference.com/history/did-benjamin-franklin-invent-bifocals-ea0f3ebea1bf582a

Benjamin Franklin invented bifocals in 1784. As announced in a letter to a friend, he called the new invention "double spectacles." The glasses allowed a person to see far or near, depending on what...

cf.libguides.com/franklin/invent

Jun 19, 2017 ... Although he made important discoveries and advancements, Ben did not "invent" electricity. He did, however, invent the lightning rod ... A modern replica pair of the type of split bifocal spectacles known to have been worn by Benjamin Franklin in the mid 1780s. Bifocals are eyeglasses with an upper and ...