Careless use of ink is the cause of much injury to library books. As a rule (to which the very fewest exceptions should be made) pencils only should be allowed to readers, who must forego the use of ink, with the inevitable risk of dropping it upon the book to its irreparable injury. The use of ink in fountain pens is less objectionable. Tracing of maps or plates should not be allowed, unless with a soft pencil. Under no circumstances should tracing with a pen or other hard instrument be permitted to any reader. Failure to enforce this rule may result in ruin of valuable engravings or maps. There is one class of books which demand special and watchful care at the hands of the librarian. These are the fine illustrated works, mostly in large folio, which include the engravings of the art galleries of Europe, and many other specially rare or costly publications. These should be carefully shelved in cases where they can lie on their sides, not placed upright, as in some collections, to lean over, and, sooner or later to break their backs, and necessitate rebinding. When supplied to readers, there should not be more than one volume at a time given out, to avoid the risk, always threatening, of careless handling or of opening one volume on top of another that is open. There should also be a printed notice or label affixed to the side cover of every illustrated work reading, "Never touch an engraving," or an equivalent warning. This will go far, by its plain reminder, to prevent soiling the pages by the fingers, a practice which rapidly deteriorates fine books, and if long continued, renders them unfit to be exhibited to clean-handed readers. All plates should be stamped at some portion of their surface (it is often done on the back) with the embossing stamp of the library, as a means of identification if abstracted from the volume to which they belong. Such books should, moreover, be consulted on a large table, or better an adjustable stand (to avoid frequent lifting or shifting of the position of the volume when inspecting the plates) and always under the eye of the librarian or an assistant not far removed. These precautions will insure far more careful treatment, and will result in handing down to a new generation of readers many a rare and precious volume, which would otherwise be destroyed or irretrievably injured in a very few years. The library treasures which cost so much to bring together should never be permitted to suffer from want of care to preserve them.