20 U.S. 453 (1822)
7 Wheat. 453
EVANS
v.
HETTICH.
Supreme Court of United States.
March 20, 1822.
468*468 Mr. Justice STORY delivered the opinion of the Court.
This case is an action for an infringement of the same patent as in Evans v. Eaton;[a] and many of the remarks in that case are applicable to this; and therefore the opinion now delivered will refer to such points only, as are not completely disposed of by the opinion already delivered. The evidence in this case does not establish, that the defendant used the plaintiff’s improved Hopperboy; but the Hopperboy used by the defendant, is asserted to be Stouffer’s Hopperboy. At the new trial, a Mr. Aby was offered as a witness by the defendant, to prove the nature and character of the Hopperboy used by the defendant; the plaintiff objected to his testimony, as incompetent, because he was sued by the plaintiff for an infringement of his patent right, under circumstances similar to those alleged in proof against the defendant. The Court overruled the objection; and the witness was then sworn on the voir dire, as to his interest in the suit; but upon a full examination, it did not appear that he was really interested; and the Court therefore permitted him to be sworn in chief. The plaintiff took an exception to this decision of the Court. The objection to the competency of Aby, so far as he has an interest from being sued, cannot 469*469 be distinguished, in principle, from that already overruled in the case of Evans v. Eaton. There is this additional circumstance in this case, that Aby was not called as a general witness, but to establish a single fact, viz. the nature and character of the Hopperboy used by the defendant. The other objection upon his answers on the voir dire, is disposed of by the single remark that he purged himself of any real interest in the event of the suit. A question was asked of this witness, on his examination in chief, whether the Hopperboy in the defendant’s mill was like the model exhibited in Court of the plaintiff’s patented Hopperboy; the plaintiff objected to the question, because such testimony could not be given in this case, for want of notice thereof. But the objection was overruled by the Court; and, in our judgment, with perfect correctness. No notice was necessary to authorize the inquiry; and if the plaintiff meant to rely on the notice required by the sixth section of the patent act, in certain cases, it is only necessary to say, that this was not within the provision of that class of cases. The question was perfectly proper under the general issue. Similar objections were taken to other witnesses; but it is unnecessary to remark on them.
An inquiry was proposed by the plaintiff, to one of the witnesses, whether one Peter Stouffer had paid the plaintiff for a license for his mill; but the Court refused to allow the question to be asked; and we see no reason why it should have been allowed, for it merely referred to an act among strangers, which ought not to prejudice the defendant. A 470*470 similar question was proposed to be asked of the same witness, whether the executors of Jacob Stouffer had paid the plaintiff for a license for the mill of Jacob; the Court overruled the question; and for the same reason, it was rightly overruled.