ITEM: Eyeglasses screw
INVENTED: 20th century USE: Joining hinges
London optician Edward Scarlett was among the first to advertise temple arms for eyeglasses around 1730. Later appendages featured a doorlike hinge that let users fold their specs for travel. The first models used metal posts to affix frames to arms. But, as the refinement of industrial threading machines like lathes continued into the 20th century, tiny stainless-steel screws took that job. Over time, the fit has become standardized: Most frames now require fasteners with a shaft diameter of 1.4 mm, while some thin wire frames use ones as small as 1.2 mm. Consider that two-thirds of American adults—about 159 million people—wear prescription glasses. That’s a lot of screws that could go loose. Fortunately, you can find a repair kit at nearly any drugstore.