Complex sentence: In their well-researched biography, du Preez and Dronfield state that Barry was born in Cork in 1789 based on Mrs Bulkley's description of her daughter as being fifteen years old in a letter dated 14 January 1805.
Split into simpler sentences: In their well-researched biography, du Preez and Dronfield state that Barry was born in Cork in 1789. This birth date is based on Mrs Bulkley's description of her daughter as being fifteen years old in a letter dated 14 January 1805.