Medieval Technology Pages - Spectacles (original) (raw)

Spectacles

Spectacles seem to have been invented in Florence in 1285 or a few years later. These were convex lenses, of help only to the far-sighted. Concave lenses of use to the near-sighted were not developed prior to the 16th century. [Cipolla 1994 p 145] The evidence for this, as noted by Carlo Cipolla, lies in a sermon given in Florence in 1306 by Father Giordano de Pisa:

"It is not twenty years since there was discovered the art of making spectacles which help you see well, and which is one of the best and most necessary in the world. I myself saw the man who discovered and practiced it and I talked with him." [Cipolla 1994 p 145]

Undated image showing a man writing with spectacles It is not clear when knowledge of the properties of lenses came into Europe. The properties both of lenses and plane, spherical, and parabolic mirrors were known to the Moslem mathematician and natural philosopher Alhazen (Ibn al-Haitham) (ca. 965-1039). [Derry and Williams 1960 p 112] [Hassan and Hill 1986 p 23] [Lindberg 1992 p 309] Alhazen's works were known both to Robert Grossteste (1168-1253) and Roger Bacon (1214-1292). Bacon is known to have experimented with convex lenses for correcting vision. [Derry and Williams 1960 p 112]

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