words are copied from the act of 1836, which in this respect was substantially the same as the act of 1870. The specification may be amended so as to make it more clear and distinct; the claim may be modified so as to make it more conformable to the exact rights of the patentee, but the invention must be the same. So particular is the law on this subject that it is declared that 'no new matter shall be introduced into the specification.' This prohibition is general, relating to all patents; and by 'new matter' we suppose to be meant new substantive matter, such as would have the effect of changing the invention, or of introducing what might be the subject of another application for a patent.
"The danger to be provided against was the temptation to amend a patent so as to cover improvements which might have come into use, or might have been invented by others, after its issue. The legislature was willing to concede to the patentee the right to amend his specification so as fully to describe and claim the very invention attempted to be secured by the original patent, and which was not fully secured thereby in consequence of inadvertence, accident, or mistake, but was not willing to give him the right to patch up his patent by the addition of other inventions, which, though they might be his, had not been applied for by him, or, if applied for, had been abandoned or waived. For such inventions he is required to make a new application, subject to such rights as the public and other inventors may have acquiredin the meantime." The court also quote with apparent approbation the remarks of Mr. Justice Grier, in Goodyear v. Day, partially reported in 2 Wall. Jr. 283. Goodyear's pat- ent of 1844 claimed only the process of vulcanizing India rubber, and inadvertently omitted to claim the exclusive use of the product. In 1849 it was surrendered, and two new patents were issued, one for the process, and the other for the composition. The validity of these re-issues came before Judge Grier. He decided that both patents were for the same invention, and, in reply to the objection that the latter patent claimed more than the original, he said : "If the latter patent
