3. If the book is of very recent issue, the publishers may furnish a signature or sheet which would make good the deficiency, from the "imperfections" left in the bindery, after making up the edition of the work. In most cases, the last named means of replacement will not be found available. The first, or buying a fresh copy, may entail a greater expense than the library authorities would deem proper at the time, and it might be preferred to continue the book in use, with a slight imperfection. The second method, more or less troublesome according to circumstances, or the extent of the matter to be copied is sometimes the most economical. Of course, it is subject to the drawback of not being, when done, a _bona fide_ or genuine copy of the book as published. This diminishes the commercial value of even the rarest book, although so fully restored as to text that the reader has it all before him, so that it supplies every requisite of a perfect copy for the purposes of a public library, or a private owner who is not a connoisseur in books. When the corners of a book are found to be broken (as often happens by falling to the floor or severe handling) the book may be restored by a treatment which will give it new leather corners. With paste or glue well rubbed in, apply thick brown paper on the corners, which, when dry, will be as hard as desired, and ready to receive the leather. Then the sides may be covered with marbled paper or cloth, and the volume is restored. When the back of a book becomes loose, the remedy is to take it out of the cover, re-sew it, and glue it firmly into the former back. This will of course render the back of the volume more rigid, but, in compensation, it will be more durable. In these cases of loose or broken backs, the study should be to save the leather cover and the boards or sides of the book intact, so as to diminish by more than one-half the cost of repair. As the volume cannot be restored to a solid and safe condition without being re-sewed, it may be carefully separated from the cover by cutting the cords or bands at their junction with the boards, then slowly stripping the book out of its cover, little by little, and treating the sheets when separated as already indicated in the chapter on rebinding.