Slide rule for exchange of weights and measures
1815
1815
1815
2000-100 BCE
1815
1893-4
1863-7
1820
1813
1775-1799 (original); 1900-1907 (model)
1990-96
1820
1705-1737
1772 (original); 1919 (model)
1819
4000-2001 BCE
1813
1814
1815
1819
1870-10
1730; 1967
1836-02
1872-08
1816
1972-3
2500 BCE
1880-120
1860-1820
1819-1820
1816
1990-95
circa 1820
1818
1066; 1876
1814
1945-50
1815
1820
3000-1500
1814
1820
1820
3000-2000 BCE
1820
1817
2000 BCE
1820
1820
1814
1820