=250.= BOOK-RESTS AND SHELF GUIDES.--Practically every librarian born before 1880 has invented a book-rest at some period of his career, and there is consequently the less need for describing more than one or two typical devices. The best-known form is the ordinary rectangular metal rest, which is made in several styles in japanned iron. Fig. 85 is the commonest form, though it is objectionable, because books are apt to be impaled upon the sharp edge and damaged, and occasionally the rest itself is lost. A better, though slightly more expensive, form is Fig. 86. By reason of the flanged side there is no danger of books being damaged, and this side can also be used as a classification guide if wanted to indicate where one class begins and another ends. A variation of the dummy mentioned in Section 247 (Fig. 82) is a plain wooden block mounted on metal angle pieces which can be made to act as a useful label-holder in classified libraries. The illustration (Fig. 87) will show the form of this device. Another form of book-rest or support is sufficiently described by the illustration (Fig. 88). =251. Book-Stands and Carriers.=--For desk and table use there are two very convenient and adjustable book-stands, which will be found useful in public as well as private libraries. One is the American stand with adjustable wire compartments, which is useful for keeping books handy for desk use or for sorting out cards, etc. [Illustration: FIG. 89.--Book-carrier hung on front of Bookcase (Section 252).] [Illustration: FIG. 90.--Book-truck (Section 253).] =252.= The other is the English adjustable book-stand which is largely used for displaying and carrying about a few books for committee or consultation purposes. As a table book-holder, this is probably the best and strongest form ever invented. As shown in the illustration (Fig. 89), the uprights slide and firmly grip a large or small number of books, according to the capacity of the holder. This contrivance has been adapted as a library book-carrier, by having strong hooks attached, which fit into staples affixed to the fronts or ends of bookcases. They are very useful for classifying and arranging books awaiting replacement or shelving. There are other forms of book-holders and carriers with fixed upright ends, but they are not so satisfactory as the adjustable forms described. =253.= In large libraries a book-truck will be found a useful appliance for moving quantities of books about, either for purposes of service or location or cataloguing. The design in Fig. 90 will explain this device sufficiently. BIBLIOGRAPHY =254. Author Marks:= Brown, J. D. Author Marks and Symbols. _In his_ Subject Classification, 1906, p. 26. Cutter, C. A. Author Marks. _In his_ Expansive Classification, 1891-93, p. 139. ---- Three-Figure Alfabetic-order Table. Library Bureau.