sentences:  His daughter, Mary Somerville was a noted science writer and polymath.He joined the Royal Navy in 1750 aboard HMS "Centurion", under Admiral First Lord Augustus Keppel, later moving to HMS "Mars", HMS "Garland" and HMS "Duke".He was commissioned a lieutenant on 20 December 1757, and later served on HMS "Eurus" off North America.He was in reserve between 1760 and 1766 and again between 1769 and 1776 with a brief break aboard HMS "Greyhound" and at the start of the American Revolutionary War he returned to service but was captured by the French in August 1778 and spent the rest of the war (1775-1783) as a prisoner of war.