Complex sentence: By 1808 he joined the Royal Navy, leaving 10 years later to became a clerk in the London shipping firm of Brodie McGhie Willcox where he become a partner in 1822.
Split into simpler sentences: By 1808 he joined the Royal Navy, being dischrged 10 years later in London. Anderson eventualy became a clerk in the London shipping firm of Brodie McGhie Willcox where he become a partner in 1822.