buildings or coating compositions? A lamp-filament of titanium and
zirconium with electric lamps or with alloys? A building-block of
cement, lime, sand, and carborundum, with building-blocks or plastic
compositions? Whether these be diagnosed as combinations or as elements
and compositions respectively, and classified accordingly, criticism
will be aroused. The point in view is that although principles of
patentability must be considered in a classification designed as an
instrument to aid in determining patentability, convenience and accuracy
of search and avoidance of voluminous cross-referencing may necessitate
some arbitrary rule of classification to meet various and changing
theories applied to the drafting and allowance of claims.

From the foregoing it will be evident that classification involves
orderly logical processes of induction (supplemented by hypothesis), of
definition and of deduction. After gathering a large number of facts
generalizations are made from them and a hypothesis is found to be
confirmed or modified by more extended research; the divisions are then
defined; by correct diagnosis of other instances (as other patents)
deductions may be drawn respecting the appropriate place for them in the
classification.

[1] An "art," in the sense of a single unitary invention, is a synonym
of process, method, and operation. The term "art" is ambiguous in
popular usage. In the phrase "useful arts" in the Constitution, it
denotes the area of endeavor to which the patent laws apply. When the
word "art" is used to specify some fragment of the useful arts, it
commonly raises different notions in different minds. It may be
correctly used to designate _any_ division of the useful arts. It is as
proper to speak of the art of grinding or the art of molding as of the
art of metal-working or the art of brickmaking.

[2] A "use" is an application of a means to substance to produce an
effect which may or may not be the necessary effect of the means in its
normal operation. A catalytic may be used to ignite gas or to convert
oleins into stearines. An ice pick may be used to hold a chalk line or
prick holes in leather, etc.

[3] By "natural law" in the useful arts is meant that uniformity of
action which is manifested whenever any particular substance in any
particular condition is brought into such relation with any particular
manifestation of energy that the force exerted modifies or prevents
modification of the for