
Theodolite used for the Principal Triangulation of Great Britain
1791
1791
1775
1830 (original); 1967 (model)
1815-1825
1795-1805
1829
1822
1780
1801-1830
1821
1775
1829
1801
1801-1830
1794
1798
1797
1805
1800
1780
1783-1800
1830
1795
circa 1808
1785-1795
1785
1776-1780
1776-1780
1776-1780
1793-1803
1821-1831
1955; 1830
circa 1805
1807
1782-1793
1785-1790
1784
1815
1784
1815
1795-1810
1893-4
1863-7
1791
1808
1786
1800
1776
1807
1787