Appleton's Cyclopedia of American Biography, published in New York from 1887 to 1889, contained biographical information about thousands of people (some famous, some more obscure) in American history.
"But thirty years after the Cyclopedia's initial publication, questions began to be raised about its reliability. . . . To date over 200 suspicious entries have been flagged. But due to the enormity of the work it's doubtful that all of the false information it contains will ever be identified" (Museumofhoaxes.com, accessed 11-21-2008).
How misinformation or post-truth was introduced into this standard reference work of the 19th century may never be clear. Over many decades Appleton's published thousands of other books that were generally considered reliable and authoritative. Therefore guilt might be associated more with the editors of this set, and individual authors of articles than with the publisher. Here is some of the scholarship devoted to unraveling the falsehoods incorporated in the work: