
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
1795
1792
2000-100 BCE
1791
1800
1790
1796
1794
1800
1800
1800
1795-1805
1792
1795
1800
1790
1802
1795
1795
1790
1792
1802
1790
1799-1802
1799
1790
1795-1805
circa 1801
1795-1805
4000-2001 BCE
mid-1800s
1705-1737
1797
1800
1791
1790-1794
1804
1799
1795