Marine Timekeeper known as 'H5' by John Harrison and Son 1770
1770
1770
1610; 1923
1712-1713
1769
1728
1735-1745
1717-1725
1720
1990-96
1763
1705-1737
1726-1728
1761-1762
c.1750
1730-1750
1752
1750
1755
1720
2000-100 BCE
1745-1755
1715-1725
4000-2001 BCE
1720-1770
1762
1750-1770
1755
1715-1725
1724
1769
1750-1766
1725-1755
1711
1745
1770
1745-1755
1755
1755
1762
1762
1730-1770
1740-1749
1710
1730
1740-1760
1761
1750
1762
1752
1752