Damp.—Books kept in damp places will develop mildew, and both leather and paper will be ruined.
Where possible, naturally dry rooms should be used for libraries, and if not naturally dry, every means possible should be taken to render them so. It will sometimes be found that the only way to keep the walls of an old house dry is to put in a proper dampcourse. There are various other methods employed, such as lining the walls with thin lead, or painting them inside and out with some waterproofing preparation: but as long as a wall remains in itself damp, it is doubtful if any of these things will permanently keep the damp from penetrating.
Bookshelves should never be put against the wall, nor the books on the floor. There should always be space for air to circulate on all sides of the bookshelves. Damp is specially injurious if books are kept behind closely-fitting doors. The doors of bookcases should be left open from time to time on warm days.
Should mildew make its appearance, the books should be taken out, dried and aired, and the bookshelves thoroughly cleaned. The cause of the damp should be sought for, and measures taken to remedy it. Library windows should not be left open at night, nor during damp weather, but in warm fine weather the more ventilation there is, the better.
Heat.—While damp is very injurious to books on account of the development of mildew, unduly hot dry air is almost as bad, causing leather to dry up and lose its flexibility. On this point the Chairman of the Society of Arts Committee says:—
“Rooms in which books are kept should not be subject to extremes, whether of heat or cold, of moisture or dryness. It may be said that the better adapted a room is for human occupation, the better for the books it contains. Damp is, of course, most mischievous, but over-dryness induced by heated air, especially when the pipes are in close proximity to the bookcases, is also very injurious.”
Dust.—Books should be taken from the shelves at least once a year, dusted and aired, and the bindings rubbed with a preservative.
To dust a book, it should be removed from the shelf, and without being opened, turned upside down and flicked with a feather duster. If a book with the dust on the top is held loosely in the hand, and dusted right way up, dust may fall between the leaves. Dusting should be done in warm, dry weather; and afterwards, the books may be stood on the table slightly open, to air, with their leaves loose. Before being returned to the shelves, the bindings should be lightly rubbed with some preservative preparation (see [chap. XXII]). Any bindings that are broken, or any leaves that are loose should be noted, and the books put on one side to be sent to the binder. It would be best when the library is large enough to warrant it, to employ a working bookbinder to do this work; such a man would be useful in many ways. He could stick on labels, repair bindings, and do many other odd jobs to keep the books in good repair.
A bookbinder could be kept fully employed, binding and repairing the books of a comparatively small library under the direction of the librarian.