“ Unquestionably, a contract for the purchase of any portion of the patent-right may be good as between the parties as a license, and enforced as such in the courts of justice. But the legal right in the monopoly remains in the patentee, and he alone can maintain an action against a third party who commits an infringement upon it.' As the assignment was neither of an undivided interest in the whole patent, nor of an exclusive right within a certain territory, it was held to be a mere license. ”

“ Any assignment or transfer, short of one of these, is a mere license, giving the licensee no title in the patent, and no right to sue at law in his own name for an infringement.'
We see no reason to qualify in any way the language of these opinions. While it is sometimes said that each claim of a patent is a separate patent, it is true only to a limited extent. ”

“ Such a division would inevitably lead to fraudulent impositions upon persons who desired to purchase the use of the improvement, and would subject a party who, under a mistake as to his rights, used the invention without authority, to be harassed by a multiplicity of suits instead of one, and to successive recoveries of damages by different persons holding different portions of the patent-right in the same place. ”