
Theodolite used for the Principal Triangulation of Great Britain
1791
1791
1795-1805
1801
1793-1803
1794
circa 1805
1798
1797
1893-4
1805
1800
1783-1800
1795
circa 1808
1792
1785-1795
2000-100 BCE
1783
1785
1785
circa 1810
1808
1807
1785-1790
1784
1784
1795-1810
1863-7
1791
1808
1786
1800
1807
1787
1790
1796
1794
1800
1800
1800
1795-1805
1807
1792
1795
1800
1790
1807
1802
1795
1795