
Theodolite used for the Principal Triangulation of Great Britain
1791
1791
1775
1780
1775
1801
1794
1798
1797
1800
1780
1783-1800
1795
1785-1795
1771-1800
1785
1776-1780
1776-1780
1776-1780
2000-100 BCE
1778
1775-1799
1783
1785
1782-1793
1785-1790
1784
1784
1791
1786
1800
1776
1787
1790
1796
1794
1800
1800
1800
1792
1795
1800
1790
1802
1795
1795
1775-1800
1790
1792
1792
1802