which covered a machine for crimping heel stiffenings of boots and shoes. Among the claims of that patent was one for the process of using that machine. Judge LOWELL held that claim to be void, because it purported to cover the mode of operating the machine, and not to cover any particular mechanism.

In Reay v. Raynor' the patent had numerous claims, all but one of which covered a corresponding number of parts of a machine for manufacturing envelopes. Some of those parts operated to feed the blanks under the table which supported the gum box, instead of over it. The fifth claim covered that operation, on the theory that feeding under the gum box was new. But Judge WHEELER held the operation to be unpatentable.

§ 6. In pursuance of the rule established in Corning v. Burden, and followed in the several later cases explained in the last section, the word "process" will not hereafter in this book be used in its generic sense of "an operation performed by rule to produce a result," but it will be used only in its narrower patent law meaning of an operation performed by rule, to produce a result, and which is or may be performed otherwise than by any particular machinery, or is performed by means not solely mechanical.' All processes which come within this definition are patentable, provided they are products of invention, and are new and useful.' That all processes, and all machines, manufactures, and compositions of matter, must possess those three requisites in order to be proper subjects of patents, will be explained at large in the next three chapters of this book.

§ 7. It was shown in Section 2 that the discovery of a law of nature is not patentable. That which was so denominated in that section is often spoken of as a "prin

1 Reay v. Raynor, 19 Fed. Rep. 310, 1884.

Ex parte Herr, 41 Off. Gaz. 465, 1887; Ex parte Young, 46 Off. Gaz. 1636, 1888.

3 Fermentation Co. v. Maus, 122 U. S. 427, 1886; Telephone Cases, 126 U. S. 533, 1888; Celluloid Mfg. Co. v. American Zylonite Co. 31 Fed. Rep. 904, 1887.

ciple," and at other times as a "scientific principle," and again as a "scientific fact," and still again as a "fact in nature." By whatever name it is called, it is certain that the thing referred to is not a material substance. It is not to be apprehended by the sense of touch, but when discovered finds a lodgment in the mind as a mental conception only. So also, a process is not a substance which can be handled. It is seen only by noting its constituent acts as they are being performed. Principles and processes are therefore alike in that they are intangible, and being so, they have sometimes been mistaken for each other.

Whether a given patent is one for a process or one for a principle, is a question upon which its validity may wholly depend. It is therefore important to ascertain what rule governs the decision of such questions: to ascertain precisely wherein consists the difference between a patent for a principle and a patent for a process. Any search for that distinction made during the first half of this century was necessarily a speculative one, for lack of authoritative adjudged cases from which to reason. Now, however, when engaged in an investigation of the point, we have recourse to five very instructive Supreme Court decisions. The proper method of conducting the inquiry seems to be, to first set down the important relevant points of each of those cases, and then to ascertain what doctrine is consistent with them all. Such hypothetical rules as are found to be inconsistent with either of the cases may safely be rejected as not true rules; but if some one proposition is found to logically underlie all five decisions, it is safe to believe that the Supreme Court will never depart from it.

§ 8. In McClurg v. Kingsland' it appears that some method was long sought, by means of which rollers or cylinders could be so cast that the metal, when introduced into the moulds, would be given a rotary motion, to the end of throwing the flog or dross into the centre instead of the circumference of the casting. The fact that rotary motion

1 McClurg . Kingsland, 1 Howard, 202, 1843.

would so result was an understood law of nature, an understood operation of centrifugal force. The problem was to produce such a motion more conveniently and more uniformly than by stirring the liquid metal with a circular movement of an implement inserted therein. That problem was solved in 1834 by James Harley, a workman in a foundry in Pittsburg, Pennsylvania. He discovered that the rotary motion desired could be imparted to melted metal by injecting that metal into a mould diagonally instead of perpendicularly or horizontally. A patent was granted to him in 1835, for "an improvement in the mode of casting chilled rollers and other metallic cylinders and cones." Litigation arose on the patent, and coming before the Supreme Court it was held to be a patent for a process.

§ 9. In O'Reilly v. Morse' it appears, as also it appears in Section 2 of this book, that Professor Morse was not the discoverer of either of the laws of nature which he utilized in his telegraph. He did, however, invent a machine by means of which those laws could be made to carry information to a distant place. That machine was dependent for success on several laws of nature, and lacking any one of them it would have failed of its result. The chief of these was the electric current discovered by Gray. The one next in importance was that discovered by Ersted and his contemporaries, and known in natural philosophy as electromagnetism. The eighth claim of Morse's patent was construed, by the Supreme Court, to be one for the use of the electric current, for marking intelligible signs at any distance. The Supreme Court held that claim to be void.

§ 10. In Mowry v. Whitney,' the following matters are set forth. It had long been known that sudden cooling of very hot cast-iron makes it hard, but brittle. On the other hand, the slow cooling of very hot cast-iron was known to make it soft, but tough. This is annealing. Cast-iron carwheels require hardened peripheries and annealed hubs

'O'Reilly v. Morse, 15 Howard, 112, 1833.

2

Mowry v. Whitney, 14 Wallace, 620, 1871.

and plates, because the first have to endure friction and the last two have to endure strain. The early attempts to subject car-wheels to both hardening and annealing produced a weak and worthless article, resulting from the law of the expansion and contraction of metals. The peripheries of the wheels were hardened by chilling them, this chilling consisting in surrounding the moulds in which the wheels were cast with a circle of iron, and with only a thin film of sand between it and the peripheries of the wheels. This iron band being a rapid conductor of heat caused the peripheries of the wheels to suddenly cool, and thus be hardened, while the plates and hubs, being inclosed in a thick mass of sand, cooled very slowly, and were thus annealed. The sudden cooling of the rims of the wheels, however, materially contracted their circumference, and that contraction forced the still hot plates to contract their diameter. Then, when the plates came to cool down, they themselves contracted still more, and thus tended to break away from the rims, which, having entirely cooled some time before, had no more contracting to do. Wheels so made were therefore weak.

In this condition of affairs, Asa Whitney, of Philadelphia, discovered in 1848 that hardness once given to iron will not be destroyed or seriously impaired by the immediate reheating of the iron and its subsequent very slow cooling, and he also conceived a process by means of which that law of nature could be utilized to obviate the evil explained in the last paragraph. That process consisted in taking the wheels from the moulds very soon after their rims were chilled, and in putting them immediately into a chamber or furnace which had previously been heated about as hot as the then heat of the wheels, and thereupon in gradually raising the temperature of all parts of the interior of the chamber or furnace and its contents to an equally high point, and finally in causing all parts of the wheels to cool with equal slowness. In accordance with the law of nature discovered by Whitney, it turned out that the third stage of this process did not destroy or seriously impair the hard

ness of the peripheries of the wheels which were subjected to it. It did, however, cause the peripheries of the wheels to re-expand in circumference, and in so doing to stretch the still hot and ductile plates back to nearly the same diameter as that they had before the rims were contracted by the chill. The fourth stage of the process then served to contract all parts of the wheels harmoniously, and the result of the whole process was to remedy the evil at which it was aimed. Mr. Whitney obtained a patent for his invention, and the Supreme Court held it to be a patent for a process, and held it to be valid.

§ 11. The case of Tilghman v. Proctor' discloses the following facts: The celebrated French chemist, Chevreul, discovered in 1813 that fat is a regular chemical compound, consisting of glycerine and three kinds of fat acids. He also discovered that fat can be separated into those, its constituent elements, by causing them to severally unite with an atomic equivalent of water. In 1853, Richard A. Tilghman, a Philadelphia chemist, discovered that those elements of fat can be caused so to unite with an atomic equivalent of water by mixing the fat with water, and by thereupon subjecting the mixture to a high degree of heat, and to such a degree of pressure as will prevent the conversion of the water into steam. In 1854 Mr. Tilghman obtained a patent, in the specification of which he announced his discovery, and described a suitable apparatus in which to utilize that discovery in connection with the discoveries of Chevreul, and claimed "the manufacturing of fat acids and glycerine from fatty bodies, by the action of water at a high temperature and pressure." The Supreme Court held that patent to be one for a process, and to be valid.

§ 11a. The Telephone Cases' set forth the following fundamental facts: It has been known for centuries that articulate sounds can be reproduced at a distance from the place where they are originally uttered, by means of two thin

Tilghman v. Proctor, 102 U. S. 707, 1880.

1888.

Telephone Cases, 126 U. S. 531,