Picture from History of the Library p. 69 (enlarged)
This is a picture of the book stacks from 1907. Notice the long desk guarding the books. The sign with numbers attached to the stacks says, Opening Hymn 30, Closing Hymn 269. I doubt hymns were sung at the opening and closing of the library, but church services could have been held in the room. Most rooms served more than one function at that time.