It took more than three centuries to figure out how to keep the undeniably useful spectacles — crystals and later glass ground to aid human vision — on the human nose. Richard Drewry, a California ophthalmologist, calls eyeglass frames “one of technology’s best examples of poor engineering design.” Sidepieces to enlist the ears were soft, then rigid, then hinged. Along with materials used in the frames, sidepieces are vital to identifying age.
Instructions
1 Look for loops on the outsides of the lens frames on the oldest eyeglasses, going back as far as the 17th century. Ribbons were tied through the loops to go around the wearer’s ears. The Chinese hung weights on the ribbons instead of looping the ears, and counterbalanced the lenses. These earliest frames might be metal, bone or leather.
2 Find rigid sidepieces that shoot straight back to rest atop the ears, and you might have glasses from as early as 1730 in England. About 20 years later, another invention had double-hinged sidepieces.
3 Test for silver frames with two-part temples that slide in and out to adjust for distance from ear to nose. They became popular from the end of the 18th century into the 19th century. The earliest had loops on the ends of the temples. A ribbon was tied between the loops to keep the spectacles on under a wig.
4 Find frames made of hard rubber to date glasses to the time of the American Civil War, when metal frames could not be imported from Europe.
5 Look to the early 20th century for the introduction of tortoise-shell frames, and later for plastics.