A given machine capable of a given ultimate result having been
invented, a claim may be drawn to cover the combination of elements
comprised in the machine. Such claim will cover the machine as a
whole. But, the fact being recognized that many machines are, after
all, composed of a series of sub-machines, and that these
sub-machines, in turn, are composed of certain combinations of
elements, and that within these sub-machines there are still minor
combinations of elements capable of producing useful mechanical
results, and that the sub-machines, or some of the subordinate
combinations of elements within the sub-machines, might be capable of
utilization in other situations than that comprehended by the main
machine, it becomes important that the inventor be protected regarding
the sub-machines and the minor useful combinations. Claims may be
drawn for the combination constituting the main machine, other claims
may be drawn for the combinations constituting the operative
sub-machines, and claims may be drawn covering the minor useful
combinations of elements found within the sub-machines. Each claimed
combination must be operative. But secondary claims cannot be made for
sub-machines or sub-combinations which are for divisional matter or
matter which should be made the subject of separate patents.