1289
Spectacles first mentioned in Pisa
The Dominican preacher Giordano da Pisa mentioned that it was not yet twenty years since the art of making reading spectacles had been discovered. His sermon is among the earliest securely datable references to eyeglasses, an invention credited to a Venetian or Pisan craftsman. The sermon's casual reference suggests that spectacles had already become common enough among educated Italians to require no further explanation.
Qalawun captures Tripoli
The Mamluk sultan stormed the crusader-held county of Tripoli, killing or enslaving the inhabitants. The last major Frankish possessions in Outremer were reduced to Acre and a few coastal castles. The thin strip of Christian Syria was about to vanish entirely. Genoese ships evacuated what refugees they could, but most of the population was trapped within the walls when the final assault came.
Block printing flourishes under the Yuan
Yuan bureaucrats printed paper money, Buddhist sutras, and government almanacs in enormous quantities. Wang Zhen would soon experiment with a revolving table of wooden movable type. The technology, half spectacle, half sledgehammer, lingered in the Chinese imagination. The sheer volume of Yuan printing laid the groundwork for a literate popular culture that would flourish even more spectacularly under the Ming dynasty that followed.
Fakhr al-Din al-Khalili advances trigonometry
Mathematicians working in the tradition of Nasir al-Din Tusi at Maragheh refined trigonometric tables to unprecedented precision, computing sine values to ten sexagesimal places. These tables, circulated in Persian and Arabic, would underpin astronomical calculation from Isfahan to Samarkand for the next two centuries. The precision of their calculations remained unmatched in Europe until the sixteenth-century work of Rheticus and the Viennese school.