Books are frequently lettered so carelessly that the titles instead of aligning, or being in straight horizontal lines, run obliquely upward or downward, thus defacing the volume. Errors in spelling words are also liable to occur. All crooked lettering and all mistakes in spelling should at once be rejected, and the faulty books returned to the binder, to be corrected at his own expense. This severe revision of all books when newly bound, before they are placed upon the shelves, should be done by the librarian's or owner's own eye--not entrusted to subordinates, unless to one thoroughly skilled. One should never receive back books from a binder without collating them, to see if all are perfect as to pages, and if all plates or maps are in place. If deficiencies are found, the binder, and not the library is responsible, provided the book was known to be perfect when sent for binding. In the Congressional Library I had the periodicals which are analyzed in Poole's Index of Periodical Literature thoroughly compared and re-lettered, wherever necessary, to make the series of volumes correspond with the references in that invaluable and labor-saving index. For instance, the Eclectic Review, as published in London, had eight distinct and successive series (thus confusing reference by making eight different volumes called 1, 2, 3, etc.) each with a different numbering, "First series, 2d series," etc., which Poole's Index very properly consolidated into one, for convenient reference. By adding the figures as scheduled in that work--prefixed by the words _Poole's Index No._ ---- or simply _Poole_, in small letters, followed by the figure of the volume as given in that index, you will find a saving of time in hunting and supplying references that is almost incalculable. If you cannot afford to have this re-numbering done by a binder in gilt letters, it will many times repay the cost and time of doing it on thin manila paper titles, written or printed by a numbering machine and pasted on the backs of the volumes. In all periodicals,--magazines and serials of every kind,--the covers and their advertisements should be bound in their proper place, with each month or number of the periodical, though it may interrupt the continuity of the paging. Thus will be preserved valuable contemporary records respecting prices, bibliographical information, etc., which should never be destroyed, as it is illustrative of the life and history of the period. The covers of the magazines, too, frequently contain the table of contents of the number, which of course must be prefixed to it, in order to be of any use. If advertising pages are very numerous and bulky, (as in many popular periodicals of late years) they may well be bound at the end of the volume, or, if so many as to make the volume excessively thick, they might be bound in a supplementary volume. In all books, half-titles or bastard titles, as they are called, should be bound in, as they are a part of the book.