
Theodolite used for the Principal Triangulation of Great Britain
1791
1791
1794
1798
1797
1800
1795
2000-100 BCE
1791
1800
1796
1794
1800
1800
1800
1792
1795
1795
1795
1792
1799
1800
1792
4000-2001 BCE
mid-1800s
1705-1737
1800
1791
1799
1795
1800
1799
1797
1797
1642-1649 (original); 1883 (model)
1936
1990-95
1610; 1923
1960-1979
1797
1668; 1924
1783; 1914
1796
1797
1799
1800
1798
1792
circa 1830
1793
1793