Complex sentence: His father was William Gibb (1736-1791), contractor; and his son Alexander Gibb (1804-1867) was a civil engineer; with his son Alexander he worked under contract on several projects as John Gibb and Son.
Split into simpler sentences: His father was William Gibb (1736-1791), contractor; and his son Alexander Gibb (1804-1867) was a Civil Engineer. He worked with his son under contract on several projects as John Gibb and Son.