In the Library of Congress the classification was originally based upon Lord Bacon's scheme for the division of knowledge into three great classes, according to the faculty of the mind employed in each. 1. History (based upon memory); 2. Philosophy (based upon reason); 3. Poetry (based upon imagination). This scheme was much better adapted to a classification of ideas than of books. Its failure to answer the ends of a practical classification of the library led to radical modifications of the plan, as applied to the books on the shelves, for reasons of logical arrangement, as well as of convenience. A more thorough and systematic re-arrangement is now in progress.
Mr. C. A. Cutter has devised a system of "Expansive classification," now widely used in American libraries. In this, the classes are each indicated by a single letter, followed by numbers representing divisions by countries, and these in turn by letters indicating sub-divisions by subjects, etc. It is claimed that this method is not a rigid unchangeable system, but adaptable in a high degree, and capable of modification to suit the special wants of any library. In it the whole range of literature and science is divided into several grand classes, which, with their sub-classes, are indicated by the twenty-six letters of the alphabet. Thus Class A embraces Generalia; B to D, Spiritual sciences (including philosophy and religion); E to G, Historical sciences (including, besides history and biography, geography and travels); H to K, Social sciences (including law and political science and economics); L to P, Natural sciences; Q, Medicine; and R to Z, Arts (including not only mechanical, recreative and fine arts, but music, languages, literature, and bibliography).
The sub-divisions of these principal classes are arranged with progressive fullness, to suit smaller or larger libraries. Thus, the first classification provides only eleven classes, suited to very small libraries: the second is expanded to fifteen classes, the third to thirty classes, and so on up to the seventh or final one, designed to provide for the arrangement of the very largest libraries.
This is the most elaborate and far-reaching library classification yet put forth, claiming superior clearness, flexibility, brevity of notation, logical coördination, etc., while objections have been freely made to it on the score of over-refinement and aiming at the unattainable.
What is known as the decimal or the Dewey system of classification was originally suggested by Mr. N. B. Shurtleff's "Decimal system for the arrangement and administration of libraries," published at Boston in 1856. But in its present form it has been developed by Mr. Melvil Dewey into a most ingenious scheme for distributing the whole vast range of human knowledge into ten classes, marked from 0 to 9, each of which sub-divides into exactly ten sub-classes, all divisible in their turn into ten minor divisions, and so on until the material in hand, or the ingenuity of the classifier is exhausted. The notation of the books on the shelves corresponds to these divisions and sub-divisions. The claims of this system, which has been quite extensively followed in the smaller American libraries, and in many European ones, are economy, simplicity, brevity of notation, expansibility, unchanging call-numbers, etc. It has been criticised as too mechanical, as illogical in arrangement of classes, as presenting many incongruities in its divisions, as procrustean, as wholly inadequate in its classification of jurisprudence, etc. It is partially used by librarians who have had to introduce radical changes in portions of the classification, and in fact it is understood that the classification has been very largely made over both in Amherst College library and in that of Columbia University, N. Y., where it was fully established.
This only adds to the cumulative proofs that library classification cannot be made an exact science, but is in its nature indefinitely progressive and improvable. Its main object is not to classify knowledge, but books. There being multitudes of books that do not belong absolutely to any one class, all classification of them is necessarily a compromise. Nearly all the classification schemers have made over their schemes—some of them many times. I am not arguing against classification, which is essential to the practical utility of any library. An imperfect classification is much better than none: but the tendency to erect classification into a fetish, and to lay down cast-iron rules for it, should be guarded against. In any library, reasons of convenience must often prevail over logical arrangement; and he who spends time due to prompt library service in worrying over errors in a catalogue, or vexing his soul at a faulty classification, is as mistaken as those fussy individuals who fancy that they are personally responsible for the obliquity of the earth's axis.
It may be added that in the American Library Association's Catalogue of 5,000 books for a popular library, Washington, 1893, the classification is given both on the Dewey (Decimal) system, and on the Cutter expansive system, so that all may take their choice.
The fixed location system of arrangement, by which every book is assigned by its number to one definite shelf, is objectionable as preventing accessions from being placed with their cognate books. This is of such cardinal importance in every library, that a more elastic system of some kind should be adopted, to save continual re-numbering. No system which makes mere arithmetical progression a substitute for intrinsic qualities can long prove satisfactory.
The relative or movable location on shelves is now more generally adopted than the old plan of numbering every shelf and assigning a fixed location to every volume on that shelf. The book-marks, if designating simply the relative order of the volumes, permit the books to be moved along, as accessions come in, from shelf to shelf, as the latter become crowded. This does not derange the numbers, since the order of succession is observed.
For small town libraries no elaborate system of classification can properly be attempted. Here, the most convenient grouping is apt to prove the best, because books are most readily found by it. Mr. W. I. Fletcher has outlined a scheme for libraries of 10,000 volumes or less, as follows:
