The selection of books to be bought at any one time will be determined by the prices at which they can be secured and consequently it is desirable to constantly study dealers’ catalogs. Worn copies of popular titles or copies that are loose in their bindings are not ordinarily wise purchases, as they soon require rebinding, and thus make the total cost exceed the first cost of a copy in reinforced binding. Subscription books are rarely worth anything like the money asked for them. If wanted they can frequently be bought from dealers in second hand books, or from jobbers in remainders and surplus stock. Books should not be bought from traveling agents. There are only a few publishing houses who employ them who would not supply their books through the regular channels of trade. “Editions de luxe” are now generally understood to be for looks only, and “library editions” are frequently so called because they are for the private and not for the public library, being put up in a way not warranted to withstand wear and tear. =Accession Book.=—The accession book, which corresponds to the invoice book of a business house, is the first of all records to be made of a book after it has been acquired by a library. The accession book aims to show the additions of each day in the exact order of their reception, without classification of any kind. One turns to it to learn what price was paid for a book, when and where it was bought, how much was paid for binding it, if it was bound after being acquired by the library, how much was paid for replacement if lost, etc. Each volume is entered on a separate line, and secures a separate accession number. By means of this number the history of any particular book can be traced. The accession book is the most permanent of the library records; entries cannot disappear as from a card shelf list, and it is of the greatest value in case of books lost or destroyed by fire. Each book should be entered immediately after it is collated and found to agree with the order and bill. The entries must be kept up to date in order to avoid loss and confusion. An accession number should be given each separate volume. Giving a single accession number to a set leads to endless confusion. A numbering machine will save time and help to prevent errors. CHAPTER IV. =CLASSIFICATION.=