
Theodolite used for the Principal Triangulation of Great Britain
1791
1791
1795
1794
circa 1805
1807
1795-1810
1863-7
1791
1808
1800
1807
1790
1796
1794
1800
1800
1800
1795-1805
1807
1792
1795
1800
1790
1807
1802
1795
1795
1790
1792
1792
1802
1790
1799-1802
1790-1810
circa 1810
1799
1806
1795-1805
1793-1803
1798
1797
1893-4
1805
1800
1795
circa 1808
2000-100 BCE
1808
1788
1801