possibilities of invention are near the limit and
will give food for further thought to all concerned with this attempt to
classify the useful arts to the point of refinement necessary to enable
this office to pass judgment with reasonable speed and accuracy upon the
approximately 75,000 applications filed each year.

_Division and arrangement in the natural sciences._--Some of the natural
sciences are said to be in what is known as the classificatory stage of
development. In some sciences the subject of classification has been
predominant and these furnish excellent examples of scientific
classification.

The much-admired classifications of zoology, botany, and mineralogy are
among the best available models of logical division,[8] systematic and
analytical arrangement. The most casual consideration of these
classifications, however, renders apparent the relative simplicity of
the task of classifying natural objects differentiated by fixed natural
laws as compared with the task of classifying the products of the
creative and imaginative faculties as applied to the useful arts. The
chimera and other animal monsters occur only as figments of the mind.
Zoological classification does not have to classify combinations of
birds, fishes, reptiles, and mammals, nor does it deal in the way of
classification with the parts of animals, nor is the question of
absolute numbers of instances a matter of moment to such a
classification, all of the members of a species being alike for
classification purposes. But any instrument of the useful arts may be
combined with some other, any part with some other part. Organizations
may be parts of some other organizations, or even mutually parts of each
other, as, for example, a pump may be a part of a lubricator, or a
lubricator may be a part of a pump. Some parts are peculiar to one
instrument, some are common to many. Every member of a species differs
from every other member. Added to this, the intellectual differences
between the persons who present the applications for patent, the
differences in their generalizing powers, the relatively broad and
narrow views of two or more persons presenting the same invention
(variations not indulged in by nature) complicate the problem of
classifying the useful arts.

_Difficulty of entitling a subclass corresponding to every
combination._--In any main class or group of the useful arts there are
always a number of characteristics that it may be desir