should be supplied in the Subject Index.

Before printing, the plan was submitted to quite a number of librarians
for criticism. Among the hundreds of points raised as to its practical
workings and usefulness there was only one in which it was not shown to
be equal or superior to any other system known. This objection applied
only to the arrangement on the shelves; not at all to the catalogues or
indexes. It was, that in this relative location, a book which this year
stands, e.g., at the end of a certain shelf; may not be on that shelf
at all another year, because of the uneven growth of the parts of the
library. This slight objection inheres in any system where the books
are arranged by _subjects_ rather than by windows, doors, shelves, and
similar non-intellectual distinctions.

In this hurriedly prepared account of his plan, the author has doubtless
failed to meet many objections which may be raised and which he could
easily answer. He would therefore ask the privilege of replying
personally to any such objections, where they arise, believing that it
will be possible to answer, if not all, at least a very large proportion.

In his varied reading, correspondence, and conversation on the subject,
the author doubtless received suggestions and gained ideas which it is
now impossible for him to acknowledge. Perhaps the most fruitful source
of ideas was the _Nuovo Sistema di Catalogo Bibliografico Generale_ of
Natale Battezzati, of Milan. Certainly he is indebted to this system
adopted by the Italian publishers in 1871, though he has copied nothing
from it. The plan of the St. Louis Public School Library, and that of the
Apprentices' Library of New York, which in some respects resemble his
own, were not seen till all the essential features were decided upon,
though not given to the public. In filling the nine classes of the scheme