Hi wee Hugh, sorry for delay in answering. Briefly I made the index that you didn't see on your visit to the library. My [work in progress] card index was originally produced for my own use, in haste, out of library hours, with some of the volumes removed before I could examine them. The library then valued the effort having it typed up. Unexpectedly my card index vanished, so it was never proof read. against the cards. The original was typed on foolscap then as this original became worn out, it was photocopied. About 10 years ago I retyped the index from a photocopy copy hoping the library would consider encouraging somebody else to finish what I started. Nothing happened regretfully. Yes you are right every volume differs, in having page numbers or not, some with contents listing, some not etc. I paged one volume in pencil but was told not to do that again.
The index was meant to follow these guide lines as it built up
1. Each reference starts with a number that is the volume number between 1 and 98.
2. Either it is immediately followed by a p for first page number, followed by that page number, followed by a comma, OR there are no page numbers usually because most of the volume is about that family, OR there is a page index in that volume, OR the volume was without page numbers.
3. Next can come a locality place-name or a house name.
4. Next can come one or more surnames. These are the equivalent of see and see also references. In practice this is not easy for a newcomer to establish a clear system earlier enough.
5. A coma signifies the next reference to that surname.
6. The letter T is used when it appears the material has been transcribed or ‘Part’ transferred elsewhere, any other reference to that surname being a more complete or final version normally.
7. The letter N is for notes that are either at the end of the tree or more often at the end of the book.
8. Those surnames that fall into the M’, Mc, Mac are treated as within one Mc section.
9. Overall advice: - Look up every surname reference, and double check the back of each book for further notes.
So to recap the references I gave you, :-Mussen is in volume 23 a Lisburn line, also Mussen turns up in volume 33, and in volume 63 (some association with an Allen) + Two items these were probably loose tucked in newspaper cuttings, more Mussen in volume 90 a Hillhall connection and volume 92 with a Lisburn connection. These last two entries could be in special bindings and be kept in the Strong room etc.
Finally If you want a copy of the index I will send it to you via PM
Good luck onwards Jim