Whether a public library be large or small, its value to students will depend greatly upon the care and completeness with which its selection of periodical works is made, and kept up from year to year. Nothing is more common in all libraries, public and private, than imperfect and partially bound sets of serials, whether newspapers, reviews, magazines or the proceedings and reports of scientific and other societies. Nothing can be more annoying than to find the sets of such publications broken at the very point where the reference or the wants of those consulting them require satisfaction. In these matters, perpetual vigilance is the price of completeness; and the librarian who is not willing or able to devote the time and means requisite to complete the files of periodical publications under his charge is to be censured or commiserated, according to the causes of the failure. The first essential in keeping up the completeness of files of ephemeral publications, next to vigilance on the part of their custodian, is room for the arrangement of the various parts, and means for binding with promptitude. Some libraries, and among them a few of the largest, are so hampered for want of room, that their serials are piled in heaps without order or arrangement, and are thus comparatively useless until bound. In the more fortunate institutions, which possess adequate space for the orderly arrangement of all their stores, there can be no excuse for failing to supply any periodical, whether bound or unbound, at the moment it is called for. It is simply necessary to devote sufficient time each day to the systematic arrangement of all receipts: to keep each file together in chronological order; to supply them for the perusal of readers, with a proper check or receipt, and to make sure of binding each new volume as fast as the publication of titles and index enables it to be done properly. While some libraries receive several thousands of serials, the periodical publications taken by others amount to a very small number; but in either case, the importance of prompt collation and immediate supply of missing parts or numbers is equally imperative. While deficiencies in daily newspapers can rarely be made up after the week, and sometimes not after the day of their appearance, the missing parts of official and other publications, as well as of reviews and magazines appearing at less frequent intervals, can usually be supplied within the year, although a more prompt securing of them is often necessary. In these publications, as in the acquisition of books for any library, the collation of each part or number is imperative, in order to avoid imperfections which may be irreparable.