Congress is given power to promote the progress of science and the useful arts. To that end it may, by all necessary and proper laws, secure to inventors, for limited times, the exclusive right to their inventions. That power has been exerted in the various statutes prescribing the terms and conditions upon which letters-patent may be obtained. It is true that letters-patent, pursuing the words of the statute, do, in terms, grant to the inventor, his heirs and assigns, the exclusive right to ...
