
Theodolite used for the Principal Triangulation of Great Britain
1791
1791
1775
1780
1775
1794
1797
1780
1795
1785-1795
1785
1776-1780
1776-1780
1776-1780
1782-1793
1785-1790
1784
1784
1791
1786
1776
1787
1790
1796
1794
1792
1795
1790
1795
1795
1790
1792
1792
1790
1785-1795
1781-1790
2000-100 BCE
1778
1777-1785
1775-1785
1783
1785
1788
1776-1780
1776-1780
1778-1780
1784
1784
1783
1784
1784