NEW YORK — The New York Public Library's archive is so massive that some of the material has never been seen except on request.

Beginning Friday, the library presents a selection of those hidden gems, a group of works showcasing the extraordinary printmaking skills of American impressionist artist Mary Cassatt.

"Daring Methods: The Prints of Mary Cassatt" includes 88 prints donated to the library in 1900 by Samuel Putnam Avery, a Manhattan art dealer who developed a close working relationship with the artist....