
Theodolite used for the Principal Triangulation of Great Britain
1791
1791
1830 (original); 1967 (model)
1815-1825
1795-1805
1801-1830
1829
1822
1821
1829
1801
1801-1830
1794
1798
1797
1805
1800
1830
1795
circa 1808
1785-1795
1785
2000-100 BCE
1813
1826
1801-1830
1801-1830
1801-1830
1801-1830
1808
1812
1805-1815
1785
1820-1830
1793-1803
1955; 1830
circa 1805
1807
1785-1790
1815
1815
1795-1810
1893-4
1863-7
1791
1808
1786
1800
1807
1787
1821