
Theodolite used for the Principal Triangulation of Great Britain
1791
1791
1830 (original); 1967 (model)
1815-1825
1795-1805
1801-1838
1829
1821
1801-1830
1822
1829
1801
1801-1830
1793-1803
1837
1794
1821-1831
1955; 1830
1835
1832
circa 1805
1798
1797
1893-4
1838
1934
1837
1805
1800
1812
1805-1815
1830
1820-1840
1795
circa 1808
1814
1840
1792
2000-100 BCE
1813
1833
1810-1840
1810-1840
1831
1835
1836
1837
1840
1826
1801-1830
1801-1830