Great care should be taken not to let grit, such as blows in at the open window from many a dusty road, be upon your duster, or you will probably find fine scratches, like an outline map of Europe, all over your smooth calf, by which your heart and eye, as well as your book, will be wounded.
"Helps" are very apt to fill the shelves too tightly, so that to extract a book you have to use force, often to the injury of the top-bands.
Beware of this mistake.

It frequently occurs through not noticing that one small book is purposely placed at each end of the shelf, beneath the movable shelf-supports, thus not only saving space, but preventing the injury which a book shelf-high would be sure to receive from uneven pressure.
After all, the best guide in these, as in many other matters, is "common sense," a quality which in olden times must have been much more "common" than in these days, else the phrase would never have become rooted in our common tongue.
Children, with all their innocence, are often guilty of book-murder.

I must confess to having once taken down "Humphrey's History of Writing," which contains many brightly-coloured plates, to amuse a sick daughter.
The object was certainly gained, but the consequences of so bad a precedent were disastrous.

That copy (which, I am glad to say, was easily re-placed), notwithstanding great care on my part, became soiled and torn, and at last was given up to Nursery martyrdom.

Can I regret it?
surely not, for, although bibliographically sinful, who can weigh the amount of real pleasure received, and actual pain ignored, by the patient in the contemplation of those beautifully-blended colours?
A neighbour of mine some few years ago suffered severely from a propensity, apparently irresistible, in one of his daughters to tear his library books.