1732-1811. English astronomer, who accurately
measured the distance from the Earth to the
Sun by observing a transit of Venus across
the Sun's face 1769. In 1774 he measured the
mass of the Earth by noting the deflection of
a plumb line near Mount Schiehallion in
Scotland. He was the fifth Astronomer Royal
1765-1811. He began publication 1766 of the
Nautical Almanac, containing tables for
navigators.