PAST CLASSIFICATIONS OF UNITED STATES PATENT OFFICE.

As under the patent laws the people of the United States assume all the
risks in granting a patent for any means of the "useful arts," a
classification that will facilitate a judgment respecting the
patentability of any means presented to the Patent Office is of peculiar
moment. The enormous extent, diversity, and refinement of the useful
arts preclude the formation of a judgment on novelty within a reasonable
time, unless the necessary comparisons with known processes and
instruments have been previously made along the lines that searches must
follow and the results of such comparisons made available in a
classification. The vast majority of available disclosures of the arts
occur in patents. Hence the Patent Office classification must be
adjusted in the main to the analysis, diagnosis, and orderly arrangement
of the disclosures of patents.

For more than 80 years United States patents have been classified. The
first published classification, promulgated in 1830, comprised 6,170
patents, divided into 16 classes. The change from a registration to an
examination system in 1836 instigated a new classification in 22
classes, including 9,800 patents. The next came in 1868 with 36 classes,
including about 75,000 patents. On March 1, 1872, a revised
classification was adopted, comprising 145 classes, including 131,000
patents. This classification is said to have been planned by Dr. Edward
H. Knight. The placing of the patents in accordance with the schedule of
classes is said to have been done by the several examiners. The class
arrangement was purely alphabetical by class titles, and the number
designations followed the alphabetical order. The names of things to be
found in the several classes were arranged alphabetically under each
class title. No attempt was made to bring the titles of allied materials
into juxtaposition or to effect other definite arrangement with
reference to subject matter in the printed schedules. A consolidated
name index supplemented the list of names by classes.

This classification of 1872 is in part the classification that now
exists, many of the same class numbers and titles being still in use.
Examiners were apparently permitted to make changes in classification to
suit their convenience without notice until 1877. In that year a
revision of the published schedule was made by a committee, resulting in
the addition of 13 new classes, and ex