Update, Bly's The Mystery of Central Park (1889).

Cover of The Mystery of Central Park
by Nellie Bly (1889)

My earlier post on Nellie Bly's only mystery novel, The Mystery of Central Park, may have had some results. The Library of Congress informed me that it has digitized its copy of the novel, which is now available through the Internet Archive. This is excellent news, as there are only three copies in US libraries.