Eyeglasses and the Discovery of the Microscope

Abstract

The phenomenon of magnification that causes objects to appear larger than their actual size was known during antiquity. Neither the date of the discovery nor the name of the person who first observed or recorded the phenomenon is known. It is speculated that the discovery resulted from a fortuitous observation that small objects appear enlarged when seen through a spherical glass vessel filled with water. This explanation stems from Roman writings on the subject. In the second century AD, Ptolemy (Claudius Ptolemaeus), an astronomer, geographer, and mathematician, wrote a treatise on optical phenomena known at that time. In this treatise, entitled Optica, he discussed magnification by glass spheres filled with water and also by pieces of glass of certain shapes. Despite this knowledge, more than a thousand years passed before glass lenses came into use. Progress in the sciences virtually came to a standstill after the second century AD and remained so until the sixteenth century. There is still no satisfactory explanation for the lack of scientific inquiry and advancement of knowledge over such a long period. Furthermore, much of the scientific knowledge of antiquity would have been lost to Western civilization had it not been for Arab scholars, who translated the ancient scientific writings into Arabic and studied them over the centuries. The Crusades of the eleventh to thirteenth centuries made it apparent to Europeans that in many respects Muslim culture was more advanced than their own. Europeans translated scientific works written in Arabic; and through this process, scientific accomplishments of the ancient Greek and Roman civilizations reappeared in the West. The rediscovered teachings of the ancient scholars were read with awe, but instead of being an incentive for renewed investigation, they were accepted as being authoritative. Several more centuries were to pass before the scientific teachings of antiquity were seriously challenged. During the Dark Ages in Europe, Alhazen, an Arabian scholar (ca. 965-1040), made significant contributions to optics by his studies of refracted light and magnification due to refraction. However, he saw no practical application for his observations. The precursor of both the microscope and the telescope were lenses for aiding vision and correcting defects in vision. Roger Bacon, an English scholar of the thirteenth century, experimented with lenses and concluded that they would be useful for aiding vision. In his Opus maius written in 1267 he stated, if a man (sic) looks at letters and other minute objects through the medium of a crystal or of a glass or of some other transparent body placed upon the letters, and this is the smaller part of a sphere whose convexity is towards the eye, and the eye is in the air, he (sic) will see the letters much better and they will appear larger ... and therefore this instrument is useful for the aged and for those with weak eyes. Unfortunately, Bacon's scientific and other scholarly endeavors brought him into conflict with the Christian religion. Bacon. who was educated at the University of Oxford, and later became a Franciscan monk, ardently pursued knowledge. He wrote on astronomy, mathematics, and physics, especially optics. He was also well versed in philosophy and theology and wrote on those subjects, too. Because some of his scientific and other writings disagreed with the teachings of the Church, Bacon was condemned to imprisonment in 1278 by the superiors of the Franciscan establishment in Paris, where he was then living. Knowledge of his activities thereafter is scanty, but it is believed that he died around 1292. He did send a copy of his Opus maius to the Pope in Rome, and fortunately this work has survived. About 1300 the first eyeglasses were produced by an unknown inventor. The invention is often attributed to either Alessandro della Spina or Salvino degli Armati, but no evidence supports such claims. The earliest unequivocal evidence of eyeglasses is not a written record, but a fresco painted in 1352 by the Italian painter Tommaso da Modena.