A listing of the 23 digitized items can be found here: http://bit.ly/lxcZun.
A full listing of the over 100 items in this collection can be found here: http://bit.ly/js4DnY
One of the items was reviewed by a grateful researcher who remarked:
This book is wonderful 'find'. It's a true exemplar of what the Internet Archive is all about: once obscurely languishing in the repository of York University Music Department's Library, it's now available to everyone.
(...And my thanks to the Library for preserving this 100-year old book in such excellent condition.)
The library is happy to oblige!