Arago , François Jean Dominique , 1786-1853 , mathematician, physicist, astronomer and politician x Arago , Francesc Joan Dominic Colby , Thomas Frederick , 1784–1852 , surveyor and army officer Kater , Henry , 1777-1835 , scientist

In 1821–1823 Thomas Colby was deputed by the Royal Society, with Captain Henry Kater, to work with the astronomers Arago and Matthieu of the Académie des Sciences to verify observations made forty years earlier connecting the triangulations of England and France. For cross-channel observations, Fresnel lamps with compound lenses 3 feet in diameter were used, and Colby's description of them influenced Robert Stevenson to adopt them in British lighthouses. ( Source: Oxford DNB).