Complex sentence: Famed frontiersman and expeditionary photographer William Henry Jackson collaborated with Hebard as an illustrator in 1933 and 1934, providing water colors and sketches for her unpublished manuscript.
Split into simpler sentences: Famed frontiersman and expeditionary photographer William Henry Jackson collaborated with Hebard as an illustrator in 1933 and 1934. He provided water colors and sketches for her unpublished manuscript.