The telescope was one of the central instruments of what has been called the Scientific Revolution of the seventeenth century. It revealed hitherto unsuspected phenomena in the heavens and had a profound influence on the controversy between followers of the traditional geocentric astronomy and cosmology and those who favored the heliocentric system of Copernicus. It was the first extension of one of man's senses, and demonstrated that ordinary observers could see things that the great Aristotle had not dreamed of. It therefore helped shift authority in the observation of nature from men to instruments. In short, it was the prototype of modern scientific instruments. But the telescope was not the invention of scientists; rather, it was the product of craftsmen. For that reason, much of its origin is inaccessible to us since craftsmen were by and large illiterate and therefore historically often invisible.
Although the magnifying and diminishing properties of convex and concave transparent objects was known in Antiquity, lenses as we know them were introduced in the West 1 at the end of the thirteenth century. Glass of reasonable quality had become relatively cheap and in the major glass-making centers of Venice and Florence techniques for grinding and polishing glass had reached a high state of development. Now one of the perennial problems faced by aging scholars could be solved. With age, the eye progressively loses its power to accommodate, that is to change its focus from faraway objects to nearby ones. This condition, known as presbyopia, becomes noticeable for most people in their forties, when they can no longer focus on letters held at a comfortable distance from the eye. Magnifying glasses became common in the thirteenth century, but these are cumbersome, especially when one is writing. Craftsmen in Venice began making small disks of glass, convex on both sides, that could be worn in a frame--spectacles. Because these little disks were shaped like lentils, they became known as "lentils of glass," or (from the Latin) lenses. The earliest illustrations of spectacles date from about 1350, and spectacles soon came to be symbols of learning.
http://cnx.org/content/m11932/latest/Although the magnifying and diminishing properties of convex and concave transparent objects was known in Antiquity, lenses as we know them were introduced in the West 1 at the end of the thirteenth century. Glass of reasonable quality had become relatively cheap and in the major glass-making centers of Venice and Florence techniques for grinding and polishing glass had reached a high state of development. Now one of the perennial problems faced by aging scholars could be solved. With age, the eye progressively loses its power to accommodate, that is to change its focus from faraway objects to nearby ones. This condition, known as presbyopia, becomes noticeable for most people in their forties, when they can no longer focus on letters held at a comfortable distance from the eye. Magnifying glasses became common in the thirteenth century, but these are cumbersome, especially when one is writing. Craftsmen in Venice began making small disks of glass, convex on both sides, that could be worn in a frame--spectacles. Because these little disks were shaped like lentils, they became known as "lentils of glass," or (from the Latin) lenses. The earliest illustrations of spectacles date from about 1350, and spectacles soon came to be symbols of learning.
