The invention of spectacles

Magnifying and burning glasses were known in antiquity, and a medieval reader with failing sight could push a convex lens of rock crystal or quartz across a manuscript word by word. Mounting a pair of lenses in front of the eyes was something new. Nobody knows who first did it. The evidence points to northern Italy, most probably Pisa, around 1290.

The best evidence is a sermon. On 23 February 1306 the Dominican friar Giordano da Pisa said that the art of making eyeglasses had been found less than twenty years earlier, and that he had seen and talked with the man who first made them. He did not give a name. A manuscript of about 1299, once in the library of the 17th-century scholar Francesco Redi, spoke of spectacles recently invented for old men whose sight had begun to fail, and it is said to be the earliest written reference.

Two men were later named as the inventor, on weak grounds. Redi appears to have altered a document so that it credited the Pisan monk Alessandro della Spina; other readers took it to mean that Spina had seen spectacles made by someone else and then made his own. In 1738 Domenico Manni promoted Salvino degli Armati of Florence, whose restored tomb calls him the inventor of spectacles, but little supports the claim.

The first spectacles were two lenses in rims riveted together at the handle ends. They had no sides, gripped the nose, and usually had to be steadied by hand. Their convex lenses corrected presbyopia, the long sight of middle age, so they served the few people who lived past their forties and could read. The oldest known picture of them is a fresco of 1352 by Tommaso of Modena showing Cardinal Hugh of Provence in rivet spectacles. By the early 16th century lenses could correct short sight as well. How they worked was explained only later, when Francesco Maurolico of Messina (1494 to 1575) showed how the crystalline lens focuses light on the retina.