Here, at p. 464:

https://archive.org/stream/johnsonsuniversa01adam#page/466/mode/2up/search/ballad+poetry

Child seems to have written the article as early as 1874, which would be about midway between his two collections. There were six later editions of the Cyclopaedia through 1897, but this isn't the sort of article likely to have been revised.

You may enjoy this as well:

auspace.athabascau.ca:8080/bitstream/.../david_gregory_fsac09short.doc