Four inches is a good height for the lower edge of all labels.

Labels stick better if the place where they are to be pasted is moistened with a solution of ammonia and water, to remove varnish or grease.

If this is done the mucilage or gum on the labels when purchased will be found usually to stick well.

After the call-number is written, varnish the label with a thin solution of shellac in alcohol.

Labels put on in this way will keep clean, remain legible, and rarely come off.
If a charging system using a pocket is adopted, no book-plate is needed, if the pocket, that is, is pasted on the inside of the front cover and has the name of the library on it.
When books are classified the call-number is written with hard pencil on a certain page, the same page in all books; a common place is the first right hand page after the title-page, and near the inner margin.
This call-number should be written with ink on the pocket and book slip, which is kept in the pocket, or on the book-plate.