Turn pin spectacles with tinted, double folding lenses, France, 1790-1850
Double folding lenses give extra protection to the eyes. The lenses on these steel wire spectacles protect the front and sides of the eye. They are tinted blue to protect from the sun. The spectacle arms are pivoted at the temple and can rotate 360 degrees. They are known as turn pin spectacles. These may have been made in France. A similar pair was used by railway passengers.