answers: about 1290
context: the second half of the 18th century and into the early 19th century. In the early 20th century, Moritz von Rohr and Zeiss (with the assistance of H. Boegehold and A. Sonnefeld), developed the Zeiss Punktal spherical point-focus lenses that dominated the eyeglass lens field for many years. In 2008, Joshua Silver designed eyewear with adjustable corrective glasses. They work by silicone liquid, a syringe, and a pressure mechanism. Despite the increasing popularity of contact lenses and laser corrective eye surgery, glasses remain very common, as their technology has improved. For instance, it is now possible to purchase frames made </s> known to have written on the magnifying properties of lenses. The development of the first eyeglasses took place in Northern Italy in the second half of the 13th century. Independently of the development of optical lenses, some cultures developed "sunglasses" for eye protection, without any corrective properties. Thus, flat panes of smoky quartz, were used in 12th-century China. Similarly, the Inuit have used snow goggles for eye protection. The first eyeglasses were made in Northern Italy, most likely in Pisa, by about 1290: In a sermon delivered on 23 February 1306, the Dominican friar Giordano da Pisa (ca. 1255–1311) wrote </s> from two closely spaced slits in his double slit interferometer. Explaining his results by interference of the waves emanating from the two different slits, he deduced that light must propagate as waves. Augustin-Jean Fresnel did more definitive studies and calculations of diffraction, published in 1815 and 1818, and thereby gave great support to the wave theory of light that had been advanced by Christiaan Huygens and reinvigorated by Young, against Newton's particle theory. The earliest known lenses were made from polished crystal, often quartz, and have been dated as early as 750 BC for Assyrian lenses such as the Layard
question: when was the first pair of glasses invented