
Theodolite used for the Principal Triangulation of Great Britain
1791
1791
1794
1795
2000-100 BCE
1791
1790
1796
1794
1792
1795
1790
1795
1795
1790
1792
1792
1790
1788
4000-2001 BCE
1705-1737
1788
1791
1790-1794
1795
1790
1642-1649 (original); 1883 (model)
1936
1990-95
1610; 1923
1788
1790-1794
1668; 1924
1960-1979
1783; 1914
1794
1793
1791
1792
1792
1790
1790
1793
1790
1788
1789
1790
1790
1788
1789
30 CE