Asayer's Balance, after Ercker, 1574.
© Science Museum / Science & Society Picture Library
This balance was made in 1962 to the instructions given in Lazarus Ercker's 'Treatise on Ores and Asaying' of 1574. The beam and shackle were forged from a 16th century sword blade. The case follows Ercker's instructions, with the inside being painted green to 'refresh the eyes after much staring at the furnace'. The ends of the beam are curved in such a way as to allow for very fine adjustment, a feature which was not incorporated in later balances of a more solid construction. The book opened in front of the balance is the celebrated 'Alchymia' of Libavius (c 1600), a compilation of all the chemical knowledge of the time. It is open at one of the pages describing apparatus used in the art of asaying, the determination of the proportion of metal in an ore.