position. It is the purpose of the Patent Office classification to
divide and arrange the body and multitudinous units of the useful arts
so that, having the question of novelty of any defined means to answer,
one may with reasonable assurance approach that portion of the rank of
arts in which it will be found if it is not new, and in propinquity to
which will also be found those means that bear the closest resemblances
to that sought for, the resemblances of other units growing less in
proportion to their distance therefrom.

Success in the fundamental aim of facilitating adequate search should
evidently at the same time reduce proportionately the danger that
interfering applications will be overlooked and also effect a
distribution of labor favorable to the acquisition of special skill.

(B) PRINCIPLES OF THE NEW CLASSIFICATION OF THE PATENT OFFICE.

THE ELEMENTS OF A PATENT OFFICE CLASSIFICATION.

A classification will be useful in proportion (1) to the pertinence to
the subject under investigation of the facts selected to be grouped
together, or, in other words, in proportion to the appropriateness of
the "basis of classification" to the subject in hand; (2) to the
convenience, stability, and uniformity of the arrangement of the
subdivisions whereby the investigator may proceed with reasonable
assurance to that portion of the rank of groups within which he will
find cognate material; (3) to the accuracy and perspicuity of the
definitions of the several divisions and subdivisions; (4) to the
completeness and reliability of the cross-referencing and
cross-notations; (5) to the uniformity, feasibility, and certainty of
the rules by which the accessions of patents disclosing one or several
inventions may be diagnosed and distributed to the appropriate divisions
of the classification in accordance with the basis adopted.

Corresponding to the foregoing analysis the theory of Patent Office
classification may be treated in five parts: (1) The principles on which
the arts shall be divided (basis of classification); (2) subdivision and
mechanical arrangement of groups; (3) definition; (4) cross-referencing
and search-notes; (5) the choice of features by which a patent shall be
assigned in the classification (diagnosis).

BASIS OF CLASSIFICATION.

The first and most vital factor in any system of classification is the
basis of division, that is, the kind of characteristics common to any
number of objects selec