would turn
up on the average about every seven years. Of course there are notable
exceptions--and especially among the class of books known as
_incunabula_, (or cradle-books printed in the infancy of printing) and of
early Americana: but it is not these which the majority of libraries are
most in search of. Remember always, if you lose a coveted volume, that
there will be another chance--perhaps many of them. The private
collector, who carries it off against you, has had no former opportunity
to get the rare volume, and may never have another. He is therefore
justified in paying what is to ordinary judgment an extraordinary price.
Individual collectors die, but public libraries are immortal.

If you become thoroughly conversant with priced catalogues, you will make
fewer mistakes than most private buyers. Not only catalogues of notable
collections, with the prices obtained at auction, but the large and very
copious catalogues of such London book-dealers as Quaritch and Sotheran,
are accessible in the great city libraries. These are of the highest use
in suggesting the proximate prices at which important books have been or
may be acquired. Since 1895, annual volumes entitled "American Book
Prices Current" have been issued, giving the figures at which books have
been sold at all the principal auction sales of the year.

There is no word so much abused as the term _rare_, when applied to
books. Librarians know well the unsophisticated citizen who wants to sell
at a high price a "rare" volume of divinity "a hundred and fifty years
old" (worth possibly twenty-five cents to half a dollar,) and the
persistent woman who has the rarest old bible in the country, which she
values anywhere from fifty to five hundred dollars, and which turns out
on inspection to be an imperfect copy of one of Barker's multitudinous
editions of 1612 to '18, which may be picked up at five to eight
shillings in any old London book-shop. The confident assertions so often
paraded, even in catalogues, "only three copies known," and the like, are
to be received with absolute incredulity, and the claims of ignorant
owners of books who fancy that their little pet goose is a fine swan,
because they never saw another, are as ridiculous as the laudation
bestowed by a sapient collector upon two of his most valued nuggets.
"This, sir, is unique, but not so unique as the other."

Buying books by actual inspection at the book-shops is even more
fascinating employ