In addition to his famous collections of Irish music, Francis O'Neill also collected books of music from the Chicago-area population of Irish immigrants. Many of these are known only from O'Neill's copy, and are slowly being digitized and made available online by the library.
The Goulding "book" is actually a merged version of four different "volumes" of tunes. The first one isn't numbered, and the others are numbered 3-5. The first book has no title page, and nobody seems to know whether it's vol. 1 or 2 of the original. It has been treated as "book 1" here. Each book has 200 tunes, and Vol.3 starts at tune 401, so the first book is probably Vol.1, and Vol.2 is the one missing, with tunes 201-400. But we won't really know this is true until someone finds Vol.2 somewhere.
The tunes are in single files here, with file names of the form BNNN_Title.abc, where B is the book number (0,3,4,5), and NNN is the tune's number (1-600). The Title has '_' (underscore) instead of blanks, initial articles (the, a, an) are lower case, and the first word of the title is capitalized. The case of the rest of each title is from the book. (This all makes it easy for software to organize the tunes in various ways.)