is for precisely the same invention, art, or discovery as that described in the first, the objection that it claims more is a mistake of fact. If the last patent differs from the first only in stating more clearly and definitely the real principles of the invention, so that those who wish to pirate it may not be allowed to escape with impunity through the imperfection of the language used in the first, there has arisen one of the cases for which it was the intention of the act of congress to provide, and the objection is worthless in point of law." Powder Co. v. Powder Works, 98 U. S. 126.
I understand that the supreme court, in the case cited, and in other cases, intend to declare that in a re-issue the same, and only the same, invention which was attempted to be secured in the original patent, but which was there imperfectly stated, and was not fully secured through inadvertence, accident, or mistake, can be restated so that the principles or details of the invention may be presented clearly and accurately; but that other inventions of the patentee, or modifications of the patented invention, which had not been attempted to be secured, or had not been applied for, cannot be embraced in a re-issue, but must be the subject of a new application; and that "courts should regard with jealousy and disfavor any attempt to enlarge the scope of an application once filed, or of a patent once granted, the effect of which would be to enable the patentee to appropriate other inventions made prier to such alteration." Railway Co. v. Sayles, 97 U. S. 554.
But if the patentee has made a palpable mistake, and has limited his real invention by a misstatement of its principles, so that be is about to lose the fruit of his labor, he should be permitted to restate, and, if need be, enlarge his specification so as to include the same invention which was plainly the subject of, but was not fully secured by, the original patent; although, literally, the enlarged invention is one which he did not apply for in his original specification, because that specification, by a misstatement of his actual invention, applied for a narrower patent than he was entitled to have.
