ID: 
2496
Maker's Name: 
Philip Harris Ltd Birmingham
Where made: 
England
Dimensions: 
3.6 × 4.4 × 4.8 cm

Steel and brass. A spherometer is used to indirectly determine the radius of curvature of a spherical surface by measuring the difference in height between the tip of the central screw and the three outer legs and making a simple calculation.