ibrarians, frequently deprives them of even those aids
which a few words of inquiry might bring forth from the ready knowledge
of the custodians in charge.

That is the best library, and he is the most useful librarian, by whose
aid every reader is enabled to put his finger on the fact he wants, just
when it is wanted. In attaining this end it is essential that the more
recent, important, and valuable aids to research in general science, as
well as in special departments of each, should form a part of the
library. In order to make a fit selection of books (and all libraries are
practically reduced to a selection, from want of means to possess the
whole) it is indispensable to know the relative value of the books
concerned. Many works of reference of great fame, and once of great
value, have become almost obsolete, through the issue of more extensive
and carefully edited works in the same field. While a great and
comprehensive library should possess every work of reference, old or new,
which has aided or may aid the researches of scholars, (not forgetting
even the earlier editions of works often reprinted), the smaller
libraries, on the other hand, are compelled to exercise a close economy
of selection. The most valuable works of reference, among which the more
copious and extensive bibliographies stand first, are frequently
expensive treasures, and it is important to the librarian furnishing a
limited and select library to know what books he can best afford to do
without. If he cannot buy both the _Manuel du libraire_ by Brunet, in
five volumes, and the _Tresor des livres rares et precieux_ of Graesse,
seven volumes, both of which are dictionaries of the choicer portions of
literature, it is important to know that Brunet is the more indispensable
of the two. From the 20,000 reference books lying open to the
consultation of all readers in the great rotunda of the British Museum
reading room, to the small and select case of dictionaries, catalogues,
cyclopaedias, and other works of reference in a town or subscription
library, the interval is wide indeed. But where we cannot have all, it
becomes the more important to have the best; and the reader who has at
hand for ready reference the latest and most copious dictionary of each
of the leading languages of the world, two or three of the best general
bibliographies, the most copious catalogue raisonne of the literature in
each great department of science, the best biographica