This is one of the oldest still-functioning devices for performing calculations with mechanical systems. It may be regarded as a precursor of modern calculators. The machine consists of a gilt brass plate carrying 55 numbered silver circles and 17 numbered silvered brass circles. It is housed in a wooden case with a crystal lid. The machine is divided into three sections: the upper section contains the numbered disks used for the operations; the central section serves as a mechanical memory; the lower section is where the calculations are performed after installing the appropriate disks. Invented by Sir Samuel Morland and built by Henri Sutton and Samuel Knibb, it was donated by Morland himself to Grand Duke Cosimo III de' Medici in 1679. The dedication to the Grand Duke contains an obvious error: it gives 1666 as the year of invention and 1664 as the year of manufacture.