英语时差：眼镜简史

When you think about inventions that have radically changed human existence, what comes to mind? Probably the wheel, the printing press, maybe the refrigerator and definitely personal computers. Then there are those more mundane things that we rarely think about, but without which we'd be much worse off. Like eyeglasses, for example. Imagine a world without glasses--many of us would walk around bumping into things and driving our cars up onto the sidewalk. So who invented glasses, and how were they first made? The truth is that nobody knows who invented eyeglasses. At some point in Italy between 1268 and 1289 someone came up with the idea, but the actual inventor remains anonymous. What we do know is that the earliest lenses were made from quartz and were usually set into bone, metal, or leather. As soon as early opticians figured out how to make glass without bubbles and other obstructions, they started making lenses out of glass.

Although glasses spread quickly throughout Europe and Asia, there was one major problem: keeping them on the wearer's face. Early glasses acted a bit like scissors, pinched onto the bridge of the nose. Ouch. It took nearly four hundred years before opticians figured out that rigid sidepieces resting on top of the ears might do the trick.

No history of spectacles would be complete without some mention of Benjamin Franklin, who invented bifocals in the 1780s. Annoyed at having to constantly switch glasses whenever he wanted to read or take in the sights while traveling, Franklin had his reading glasses cut in half and fused with his distance glasses. Now that's American ingenuity for you.