
Theodolite used for the Principal Triangulation of Great Britain
1791
1791
1830 (original); 1967 (model)
1815-1825
1795-1805
1801-1830
1829
1822
1780
1821
1829
1801
1801-1830
1794
1832
1798
1797
1805
1800
1780
1783-1800
1830
1795
circa 1808
1785-1795
1835
1785
1834
1834
1834
2000-100 BCE
1813
1826
1801-1830
1801-1830
1801-1830
1801-1830
1808
1934
1812
1805-1815
1783
1785
1820-1830
1793-1803
1821-1831
1955; 1830
1835
circa 1805
1807
1782-1793