Complex sentence: The artist may have been inspired by the sight of firework displays along the Hudson River in the fall of 1909, commemorating Henry Hudson's discovery of the river in 1609 and the launching of Robert Fulton's steamboat "Clermont" in 1807.
Split into simpler sentences: The artist may have been inspired by the sight of firework displays along the Hudson River in the fall of 1909. These were commemorating Henry Hudson's discovery of the river in 1609 and the launching of Robert Fulton's steamboat "Clermont" in 1807.