Lovely antique Speherometer dating from the early 20th century. Spherometers were used by fob watch maker's and opticians to assess the curve on a piece of glass or a lens. The piece of glass in question is pressed flat to the pointer on the top of the instrument. This moves the dial and provides a reading.
The face reads "CRYSTEX. British Made. Patent". There are two scales + and - for concave and convex lenses. There is a loop on the opposite edge to the pointer which would allow for it to be attached to a fob chain.
The instrument is in good condition for its age. It is in working order although I cannot guarantee its accuracy - it is being sold as a decorative collectable item rather than an accurate scientific instrument. The outer casing is made of steel which has been lightly cleaned and polished. The glass face is generally clean with some light surface scratches. The face itself is in good condition and the instrument displays very well.
Approximate Measurements :
Diameter : 2" / 5cm
The best description comes from the photos so please look at them all carefully for the best description and if you have any questions please ask.