Bank of England bullion balance, devised by J Barton, 1820.
© Science Museum / Science & Society Picture Library
This balance features a steel beam 28 inches long inscribed on one face 'Bank of England ad 1820' and on the reverse face 'J Barton, Invr. AD 1820; Maudslay and Co. Fecerunt'. It has fitted steel knife edges, and pan shackles with double steel bearing planes. The device incorporates a downward pointer and gravity screw bobs for sensitivity adjustment.