
Theodolite used for the Principal Triangulation of Great Britain
1791
1791
1794
circa 1800
1798
1797
1791
1800
1796
1800
1794
1800
1800
1800
1792
1795
1800
1802
1795
1795
1792
1802
1799-1802
1793-1803
1799
1796-1798
1796-1797
1802
1795
1792
2000-100 BCE
1990-96
1800
1791
1799
1795
1800
circa 1801
1797
1799
circa 1795
circa 1800
1791-1792
1792
mid-1800s
1794
1772 (original); 1919 (model)
1801
1705-1737
1775-1799 (original); 1900-1907 (model)
1797