Increase

Strong convex lenses are often used as magnifying glass. The first magnifying device was used approximately 2000 years ago. In ancient Greek and Roman documents describes how to increase the items you can use a water-filled round glass vessel. Entirely made of glass lenses appeared much later and probably were first used in the eleventh century by monks who worked on the manuscripts. At the end of the XIII century magnifying glass with slight enlargement have already been used in glasses to correct hyperopia. However technique of fabrication of concave lenses for the correction of myopia was invented only in the early fifteenth century XV v.