achine the claim also specifies acts not
performed by the machine, the classification should be in the class or
subclass in which the process belongs. (See Rule 19.)

Example: Thus a claim for a method of rolling an iron plate
which consists in passing an iron blank between a pair of
rolls arranged horizontally in juxtaposition one above the
other and geared together so as to rotate in opposite
directions, and causing an idle roll supported in bearings
on the roll-housings to bear against the central portion of
the surface of one of the first pair of rolls on the upper
side thereof, should be classified as a rolling-mill, while
if to that claim were added the steps of doubling the sheet
after one passage between the rolls, again passing between
the rolls, again doubling, and then passing the now
four-ply pack between the rolls sidewise or turned 90 per
cent to the direction in which it had previously been fed,
the classification should be with processes of sheet-metal
manufacture.

(27) In the absence of settled rules defining permissible joinder of
inventions, there may be in one patent claims for one or more or all of
the classes of invention named in the statute, to wit, machine, art,
manufacture, and composition of matter. There may also be claims to
several more or less related inventions in the same statutory class of
invention but each belonging to a different industrial art. (1) Where
different main classes are involved, the patent will be classified by
the most intensive invention, without regard to the statutory class to
which it belongs. (2) Where different subclasses of the same class are
involved, the patent will be classified in that one of the several
subclasses defined to receive the several inventions which stands
highest in the schedule of subclasses.

(28) Where a patent contains claims for all or a plurality less than all
of the statutory classes, the general rule of preference or superiority
of the several classes of subclasses is that represented by the
following order, to wit: (1) Machine (or other operative instrument);
(2) Art; (3) Manufacture; (4) Composition of matter. This order is, in a
general way, the order of intensiveness of the several kinds of
invention. (See Rules 29-35.)

Example: An automatic screw-machine, peculiarly adapted to
carry out a process of making a novel form of machine-screw
out of a new iron alloy, and having