Complex sentence: Travelling alone, the 22 year-old Campbell arrived in Melbourne in June 1840, on the "Statesman"; the Pinkerton family of six people had arrived earlier, on the "Superb", in December 1839.
Split into simpler sentences: Travelling alone, the 22 year-old Campbell arrived in Melbourne in June 1840, on the "Statesman". The Pinkerton family of six people had arrived earlier, on the "Superb", in December 1839.