Thanks indeed to Joe for taking the trouble to edit all that!

As far as I can see, the text from the 1900 Johnson's Cyclopedia reprinted in Journal of Folklore Research, 31.1/3 (1994) pp 214-222 is almost identical, apart from having an updated bibliography, including the first four volumes (up to 1892) of Child's own ESPB(so presumably it was last revised before the first part of vol. 5 came out in 1894). The only differences I have spotted in the essay itself (apart from a couple of changes in punctuation) are that the sentence about the date of "Sir Patrick Spens" is omitted in the later version (in keeping with Child's conclusion in vol. 2 of ESPB that it is probably not historical), there is a different list of languages in which "May Colvin" is found ("Danish, Norwegian, Swedish, Icelandic, Dutch, Low German, Spanish, Portuguese, Italian, French, Polish, Servian, Bohemian, Wendish, Magyar, and there are traces of it in other languages"), and "so august an hypothesis" in the same paragraph becomes "so stupendous an hypothesis".