diaphragms, made of metal or membrane, and attached at their centres to the respective ends of a tightly drawn cord or wire; and that when a person speaks near and toward one of those diaphragms, the sound vibrations which are produced by his voice cause that diaphragm to vibrate correspondingly; and that those corresponding vibrations are transmitted, along the cord or wire, to the other diaphragm, and cause it also to vibrate correspondingly; and that the second diaphragm thus vibrating causes corresponding vibrations in the air adjacent thereto; and that when those vibrations strike upon the drum of the ear of a listener, they cause him to hear what was spoken toward the first diaphragm. Instruments like this are called string telephones; and they utilize that law of nature which causes such diaphragms as those employed therein, to copy and to transmit the vibrations of air which occur adjacent thereto. It has been known ever since 1831, when it was discovered by Michael Faraday, that when an armature is moved in front of an electro-magnet which is being magnetized by an electric current passing through its coil, the motion modifies the current, and that those modifications correspond to the movements of the armature in duration, in direction, and in strength; and it has long been known that the electric current thus modified will cause correspondingly modified movements in the armature of another electro-magnet through the coil of which the electric current thus modified is also passing. At this stage of knowledge of the relevant laws of nature, Alexander Graham Bell invented his telephone. That invention consisted in mounting two such diaphragms as those of the string telephone, upon two such armatures as those described in the last sentence, and thus enabling one of those armatures to transmit, and the other one to receive, such minute and exceedingly variant vibrations as those caused in the air by the human voice; and it also consisted in the process of transmitting sounds telegraphically, by causing electrical undulations, similar in form to the vibrations of the air caused by the sounds, to occur upon the conducting wire.

Mr. Bell obtained a patent for that invention, in 1876, and the Supreme Court held it to be a patent for a process, as well as for an apparatus, and held the process claim to be valid.

§ 12. The last five sections present five cases, covering five subject-matters of claim, four of which the Supreme Court held to be patentable processes, and one of which that tribunal held to be an unpatentable principle, or law of nature. To learn the controlling distinction between a claim for a process and a claim for a principle, it is therefore sufficient to ascertain precisely wherein consists the controlling difference between the eighth claim of Morse, on the one hand, and the claims of Harley, Whitney, Tilghman, and Bell on the other.

That difference does not consist in the fact that Harley, Whitney, and Tilghman each discovered one of the laws of nature which he utilized, while the laws which Morse utilized were discovered by others; because the Supreme Court did not rest its decision in the Morse case on the ground that he was not the discoverer of the electric current, but on the ground that, being a power in nature, it was not patentable to any person. Neither does that difference consist in anything outside of the use of laws of nature, because all five claims extended to accomplishing results by means of such law or laws, regardless of the particular apparatus used in the respective processes. The fact that diagonal injection of melted metal into a cylindrical mould will give that metal à rotary motion; the fact that moderate reheating of a car-wheel will not destroy its chill; the fact that very hot water will separate the elements of fat; the fact that mechanical motion may cause electrical undulations ;every one of these is just as truly a law of nature, just as truly a "principle," as is the fact of the electric current. Nor was the apparatus described by Harley, Whitney, Tilghman, and Bell, respectively, for the purpose of utilizing the first four of these laws, respectively, claimed as their sole respective inventions, any more than the particu

lar telegraph described by Morse was made essential to his eighth claim.

§13. There is apparently but one radical distinction between the claims of the four patents of Harley, Whitney, Tilghman, and Bell, on the one hand, and the eighth claim of Morse on the other. That distinction is as follows. Harley, Whitney, Tilghman, and Bell each produced a process which utilized several laws of nature, and each of them claimed the entire process he produced, including the use of all those laws in the order and method described. Morse also made an invention which utilized several laws of nature, but instead of claiming his combined and methodical use of all those laws, his eighth claim was construed as confined to one of them alone. This difference, taken in connection with the fact that the Supreme Court sustained the patents of Harley, Whitney, and Tilghman, and overthrew the eighth claim of Morse, and taken in connection with the fact that no other relevant and important difference can be detected, points to the soundness of the doctrines stated in the next section, and illustrated in the section following that.

§ 14. A patent for a process is a patent for the described combined use of all the laws of nature utilized by that process. A patent for a principle is a patent for one only of the laws of nature used in a process. If a patent for a principle were granted and sustained, it would be much broader than a patent for a process, because it would cover all processes which aim at the same result, and which use the particular law of nature covered by the patent for a principle, no matter in what combination with other laws. A patent for a process, on the other hand, covers only its own method of using all of the laws of nature which it utilizes. To grant and sustain a patent for a principle, would induce an inventor to guess which of the laws of nature used in his process will always be found indispensable, and guessing rightly, would enable him, by claiming that particular law, to suppress all subsequent processes using it: to suppress all subsequent invention in the same field until

such time as his patent might expire. A patent for a process, on the contrary, leaves the field open to ingenious men to invent and to use other processes using part of the laws used by the patented process, or using all of them in other combinations and methods.

§ 15. An illustration of the doctrines of the last section exists in the matter of the eighth claim of Morse, when considered in connection with other telegraphs than his. The subject of that claim was construed to be the use of the electric current for marking signs at any distance. The electric current is one thing, and electro-magnetism is another. The first was discovered by Gray, in 1729, but the existence of the latter was not known till ninety-one years later. Morse used both in his telegraph, but his eighth claim was construed to cover the electric current with or without the other. But without electro-magnetism Morse's telegraph would not work. After Morse came Bain, who invented a telegraph which used the electric current, but did not use electro-magnetism. Its recording apparatus operated electro-chemically, and not electro-magnetically like that of Morse. Bain's telegraph could work with a much feebler current than could that of Morse, and therefore the relay batteries of the latter were not wanted. The two telegraphs had nothing in common except that both used the electric current. If the eighth claim of Morse had been sustained as construed, it would have covered Bain's and every other electric telegraph capable of marking signs at a distance. On the other hand, had that claim been so drawn as to cover the combined use of all the laws of nature utilized by the telegraph of Morse, when used as he used them, then it would have been a claim for a process, and not being obnoxious to either of the weighty objections which are set forth in the opinion of the Supreme Court, it would doubtless have been sustained by that tribunal. In that case, however, it would not have been infringed by the telegraph of Bain, nor by any other which, like his, dispensed with one or more of the laws of nature necessary to the process of Morse.

§ 16. Machines and improvements of machines constitute the subjects of a majority of the American patents heretofore granted. A machine is a combination of moving mechanical parts, adapted to receive motion, and to apply it to the production of some mechanical result or results. All the parts of a machine may be old while the machine as a whole, and also the sub-combinations which are contained therein, are proper subjects of patents.' An improvement of a machine may consist of an addition thereto, or in a subtraction therefrom, or in substituting for one or more of its parts something different, or in so rearranging its parts as to make it work better than before. Whether or not a given improvement is a patentable one will always depend upon several considerations. In order to be so it must, first of all, be an invented improvement, as distinguished from one which is the product of mere mechanical skill in construction. This point of law is explained at large in the next chapter. So also it is explained in the chapter on infringement what improvements can be used, and what improvements cannot be used, without infringing the patents for the machines improved upon, if the latter happen to be patented. It is enough to say in this chapter, that patents are not void merely because they cover processes or things which include old inventions,' and that an improvement may or may not be an invention, and in either case may or may not be an infringement of a patent covering the machine improved.

17. The word "manufacture has a much narrower signification in the American patent laws than it has in those of England. In the latter it includes everything made by the hand of man, and also includes processes of manufacture. According to the former, processes are patentable because they are arts, while some of the things made by the hand of man are patentable as machines, and some others are patentable as compositions of matter, and

Cantrell v. Wallick, 117 U. S.

694, 1885.

2 Cochrane v. Waterman, 1 Mc

Arthur's Patent Cases, 53, 1844.

3 Cantrell v. Wallick, 117 U. S. 694, 1885.