Complex sentence: The first set of forty watercolours were completed by January 1843, reaching the New Zealand Company in London in September 1843; it was acquired by the Alexander Turnbull Library in 1981.
Split into simpler sentences: The first set of forty watercolours were completed by January 1843, reaching the New Zealand Company in London in September 1843. The New Zealand Company set was acquired by the Alexander Turnbull Library in 1981.