Great Inventions - Bifocal Glass

Benjamin Franklin invented bifocal glasses in the 1700s. He was nearsighted and had also become farsighted in his middle age. Tired of switching between two pairs of glasses, Franklin cut the lenses of each pair of glasses horizontally, making a single pair of glasses that focused at both near regions (the bottom half of the lenses) and far regions (the top half of the lenses). This new type of glasses let people read and see far away; they are still in use today.