Various kinds of stamps are used, ink, embossing and perforating. The ink ones, usually applied with rubber dies, are not altogether satisfactory when used with ordinary aniline endorsing inks, as they can be erased. Printers’ ink is more satisfactory, but it takes some time to dry, and requires metal stamps to make it work easily. The ink used by the Post Office when applied with a metal stamp has been found effective. But for their expense embossing stamps are most satisfactory, and of the various kinds of these the perforating stamp formed like a pair of nippers is the easiest to apply. Whatever kind of stamp is used, it should be made in a circular shape, as in whatever position it is applied it never appears to be upside down or uneven, as other shapes too frequently do. Every library should select certain fixed pages on which the stamps are to be placed, and every title-page, first and last pages of text, and all plates should be stamped. As a rule too much time is wasted in stamping library books, and it will be found quite enough to stamp the places indicated, and use a blind embossing stamp for the boards. =222.= In certain books it is desirable to insert special labels for the instruction of the staff and as a gentle warning to readers; for example: +----------------------------+ | | | =Notice to Staff.=--This | | book is to be examined on | | its return to the library. | | | +----------------------------+ FIG. 66.--Warning Label. This is especially useful in the case of books containing plates of art subjects which are liable to theft or disfigurement. In reference books with large folding maps or plates, the following label, which is attached to each map or plate, has proved to be serviceable: +--------------------------------------------+ | | | CROYDON PUBLIC LIBRARIES. | | | | =FOLDING MAP OR PLATE.= | | | | Please =unfold carefully= to avoid | | tearing. In =re-folding,= be sure you | | return to =original folds=. If a | | reference book, ask the assistant to do it | | for you, rather than re-fold wrongly. | | | +--------------------------------------------+ FIG. 67.--Map or Plate Label. =223. Process Checking.=--Many libraries keep a complete check of the processes through which a book passes from its receipt from the bookseller to its issue to the public, in the form of a rubber stamp which is impressed upon the back of the title-page, or at some other convenient place in the book: