“ The jury cannot compromise the matter, or halt between two opinions;-they must decide that the fact is so, or is not so; and if the latter be cause of objection to the credit of the witnesses, it would amount to the confounding of the questions of competency, and credibility; for the effect would be the same, whether the Court refused to permit the witnesses to testify on the ground of incompetency, or the jury should reject their testimony, when given, on that of want of credibility. ”

“ The inventor of the original machine, if he has obtained a patent for it, and all persons claiming under him, may lawfully enjoy all the benefits of that discovery, notwithstanding the improvement made upon it by a subsequent discoverer. If he has not chosen to ask for a monopoly, but abandoned it to the public, then it becomes public property, and any person has a right to use it. The inventor of an improvement may also obtain a patent for his discovery, which cannot legally be invaded by the inventor of the original machine, or by any other person. ”

“ The sentence following immediately that which has been relied on by the defendant's counsel seems to explain it, and to fortify the construction, which we have given to it. Upon the whole, we are of opinion, that the question, who is the original inventor of the Hopperboy? is left open by the Supreme Court, and is now to be decided by the jury. If, then, the jury should be of opinion upon the evidence, that the Hopperboy which the defendant uses, was invented, and was in use, prior to the discovery of Oliver Evans, then your verdict ought to be for the defendant. ”

“ These objections have been pressed so far beyond their just limits, as to require from the Court an explanation of their real value. Where the evidence of witnesses opposed by other witnesses is relied upon, by either side, to prove a particular fact, the jury must necessarily weigh their credit, in order to satisfy their own minds on which side the truth is most likely to be ”

“ The next reason is, to put every citizen upon his guard, that he may not, through ignorance, violate the law, by infringing the rights of the patentee, and subjecting himself to the consequences of litigation. ”

“ The next objection to the construction is, that the act of the Legislature of Pennsylvania, of 1787, conveyed to Oliver Evans the original Hopperboy, and consequently the existence and use of the Stouffer Hopperboy, at a period prior to the plaintiff's discovery, cannot now be urged to invalidate his patent. It is by no means to be admitted that the act operates to make such a transfer. ”

“ The time of its discovery. (3.) The kind of machine used by the defendant. (4.) The time of its discovery and use.
1st. As to the first, the Court has no observations to make, except that if you should find a verdict for the plaintiff, you will give the actual damages which the plaintiff has sustained, by reason of the defendant's use of his invention, which the Court will treble.
2d. The evidence applicable to this head, if believed by the jury, proves, that in 1783, Oliver Evans commenced his investigation of the subject of an improvement in the manufactory of flour ”

“ He has sinned already, if he has invaded the plaintiff's right, and it is too late to convince him of his error, if he must be a victim of it, for the want of that light, which is now shed upon the act long after his supposed transgression. ”