known. But in substantial accordance with that published plan, the
process of revision has proceeded for more than 14 years until
approximately 50 per cent of the patents (including incomplete work)
have been placed in revised classes.

PRECEDENTS AND AUTHORITIES.

No effective precedents have been found in any prior classifications of
the arts. The classifications of the principal foreign patent offices
have not been materially different in principle from the United States
Patent Office classifications of the past.

The divisions found suitable for book classification for library use,
have not been deemed adequate to the exactness and refinement essential
to a patent office classification of the useful arts. The systems of
class and subclass sign or number designations of the modern library
classifications, with their mnemonic significance, afford the most
important suggestions to be drawn from library classification. None of
these systems of designation has been adopted, (1) because of a serious
doubt as to the availability of such designations by reason of the
length or unwieldiness to which they would attain in the refinements of
division necessary in a patent office classification, and (2) because of
the enormous amount of labor necessary to make the change from present
practice.

The best analogies are in the known (but changing) classifications of
the natural sciences, and in them the problems are so different that
they can serve only to illustrate general principles. The broad
principles of classification are well understood. The authorities are
the logicians from the ancient Aristotle to the modern Bentham, Mill,
and Jevons. The effort of the Classification Division has been to adapt
and apply these well-known principles to the enormously diversified
useful arts, particularly as disclosed in patents and applications for
patents.

DEFINITION OF SCIENTIFIC CLASSIFICATION.

It may be well to insert here an authoritative definition: "A scientific
classification is a series of divisions so arranged as best to
facilitate the complete and separate study of the several groups which
are the result of the divisions as well as of the entire subject under
investigation." (Fowler, Inductive Logic.)

Investigation and study of any subject will be facilitated if the facts
or materials pertinent to that subject be so marshaled and arranged that
those most pertinent to it may appear to the mind in some form of
juxta