Two pairs of spectacles, 1800-1850.
© Science Museum / Science & Society Picture Library
The pair of spectacles shown to the left have sliding steel frames with small loops for a riband to pas behind the head. The pair on the right have silver frames with turnpin sides, and are dated c 1850. Spectacles have been in use in the West for at least 700 years. The earliest had convex lenses, and were designed to beworn by people with long sight, to help them focus on nearby objects. Later, concave spectacle lenses were made for people with short sight. In 1784 Benjamin Franklin (1706-1790) invented 'bifocals' - spectacles split into two parts, each with a different focal length.