patent for substantially the same thing
an interference is declared and the respective parties must present
proofs in support of their claims. The question between them is
priority of invention. The proceeding then is much like an equity
trial with perhaps a wider latitude in admitting evidence bearing on
the inquiry.

The applicant, if dissatisfied with the rejection of his claim by the
first examiner, or with the decision in an interference case, can
appeal to the board of the examiners-in-chief, and if dissatisfied
with their decision he may appeal to the commissioner in person, and
if still dissatisfied he can appeal to the Court of Appeals of the
District of Columbia. All appeals must be taken from the patent office
within a year, or a shorter period, if one has been fixed in a
decision.

The decision of the commissioner of patents in granting a patent is
not conclusive that the inventor is the first and original inventor,
but only prima facie, that is, in the absence of other evidence to the
contrary. Consequently, the question of patentability in every case
may be reexamined in the courts. In the early days of administering
the patent law an inventor often applied to a court for an injunction
to prevent an infringer from continuing his work. The court, assuming
that the patent had been properly granted, did not hesitate, on
adequate proof of the infringement to grant the injunction. The courts
were not slow in finding out that patents were sometimes granted that
ought not to have been, and so the practice was changed and patentees
were required to establish their right to a patent in a court of law
before a court would enjoin an infringer, except in very clear cases.
These hearings in the courts to decide the claims of patentees, are
often prolonged, running through years to collect testimony, and are
appealed from one court to another finally reaching the supreme
federal tribunal. After a patent is thus judicially established
injunctions are readily granted against all infringers.

=Payment.=--In making payment the parties to an agreement always have
in mind cash, unless they otherwise agree. Not every kind of money can
be used, nor only in limited amounts. Thus, if one owed another a
thousand dollars he could not deliver to him, unless he were willing
to accept them, one thousand silver dollar pieces, but only ten of
them. Nor can a debtor compel his creditor to receive one cent and
five cent pieces to a