used are packed closely together, and are seldom removed from the shelves.
In hot climates metal has the great advantage of resisting the attacks of insects. Slate is used in the Fitzwilliam Library at Cambridge; and papier-mâché shelves might answer for light books, though we have not heard of its having been tried. It is unnecessary to have partitions running from top to bottom of the double cases dividing the shelves on one side from those on the other. The shelves, however, should not be made to go right through the case, but must be separate, so that if necessary the shelves on one side may be placed at different heights to those on the other. All shelves should be movable, in order that the utmost freedom may be obtained for the arrangement and classification of the books.
The shelves intended for the reception of rare works, or those valuable for their bindings, should in all cases be padded. In the British Museum all the shelves are covered with cowhide, and two square pads of leather are also provided for each shelf, to prevent the end books rubbing against the upright divisions. In some libraries where leather could not be afforded Canton flannel has been used, but this is not recommended, as it is a suitable habitat for moths. Falls should be of some cheaper material than leather, or they will hardly repay their cost; at the same time they must not be dust-traps. Roller blinds, which are fixed inside the top cornice, are in use in many libraries, and keep much of the floating dust away from the books.
