Unfortunately, we do not have the actual illustration. We only know of a drawing rendered by one of Whitman’s friends, the Providence artist Rosa Peckham Danielson.
The sketch was completed from memory when Rosa traveled to Europe to study art in 1874. During her trip, she met the English Poe biographer, John Henry Ingram, who was already well acquainted with Whitman through an intense letter correspondence. Rosa had rendered a sketch of Whitman for Ingram that he described in a letter to Whitman in September, 1874: “She [Rosa] very kindly sketched me a portrait of you, & although in ‘a dim religious light,’ I feel is something like you.”
I have been searching both Whitman and Ingram’s collected papers at various institutions for this sketch, if it even survives. My hope is that it will turn up somewhere, someday, so that we can view through the eyes of an artist and friend of Whitman’s, her potentially last rendered portrait.