
Theodolite used for the Principal Triangulation of Great Britain
1791
1791
1794
circa 1800
1798
1797
1825
1808
1808
1809
circa 1805
1807
1815
1815
1795-1810
1810-1817
1791
1800
1807
1821
1805
1796
1800
1794
1800
1800
1812
1800
1795-1805
1807
1812
1792
1795
1800
circa 1808
1807
1814
1802
1795
1795
1816
1792
1802
1799-1802
1797-1804
1793-1803
1795-1805 (original)
1815-1825
1799
1806
1805