Two pairs of spectacles, English, mid 18th-19th century.
© Science Museum / Science & Society Picture Library
One pair (c 1750-1830) has a steel frame while the second pair is made of siver. Spectacles have been in use in the West for at least 700 years. The earliest had convex lenses, and were designed to be worn by people with long sight to help them focus on nearby objects. Later, concave spectacle lenses were made for peole with short sight. In 1784 Benjamin Franklin (1706-1790) invented 'bifocals' - spectacles split into two parts, each with a different focal length.