ous argument.

Opinion of the Court.

So, too, this court has denied invention to one who applied the principle of an ice-cream freezer to the preservation of fish. Brown v. Piper, 91 U. S. 37; to another who changed the proportions of a refrigerator in such manner as to utilize the descending instead of the ascending current of cold air, Roberts v. Ryer, 91 U. S. 150; to another who employed an old and well-known method of attaching car trucks to the forward truck of a locomotive engine, Pennsylvania Railroad v. Locomotive Truck Co., 110 U. S. 490; and to still another who placed a dredging screw at the stem instead of the stern of a steamboat, Atlantic Works v. Brady, 107 U. S. 192. In Tucker v. Spalding, 13 Wall. 453, the patent covered the use of movable teeth in saws and saw plates. A prior patent exhibited cutters of the same general form as the saw teeth of the other patent, attachable to a circular disk, and removable as in the other, the purpose of which patent was for the cutting of tongues and grooves, mortices, etc. The court held that if what it actually did was in its nature the same as sawing, and its structure and action suggested to the mind of an ordinarily skilful mechanic this double use to which it could be adapted without material change, then such adaptation to a new use was not new invention, and was not patentable.

Upon the other hand, we have recently upheld a patent to one who took a torsional spring, such as had been previously used in clocks, doors, and other articles of domestic furniture, and applied it to telegraph instruments, the application being shown to be wholly new. Western Electric Co. v. La Rue, 139 U. S. 601. So, also, in Crane v. Price, Webster's Pat. Cas. 409, the use of anthracite coal in smelting iron ore was held to be a good invention, inasmuch as it produced a better article of iron at a less expense, although bituminous coal had been previously used for the same purpose. See also Steiner v. Heald, 6 Exch. 607.

Indeed, it often requires as acute a perception of the relation between cause and effect, and as much of the peculiar intuitive genius which is a characteristic of great inventors, to grasp the idea that a device used in one art may be made

Opinion of the Court.

available in another, as would be necessary to create the device de novo. And this is not the less true if, after the thing has been done, it appears to the ordinary mind so simple as to excite wonder that it was not thought of before. The ap parent simplicity of a new device often leads an inexperienced person to think that it would have occurred to any one familiar with the subject; but the decisive answer is that with dozens and perhaps hundreds of others laboring in the same field, it had never occurred to any one before. The practised eye of an ordinary mechanic may be safely trusted to see what ought to be apparent to every one. As was said by Mr. Justice Bradley, in Loom Company v. Higgins, 105 U. S. 580, 591: "Now that it has succeeded, it may seem very plain to any one that he could have done it as well. This is often the case with inventions of the greatest merit. It may be laid down as a general rule, though perhaps not an invariable one, that if a new combination and arrangement of known elements produce a new and beneficial result never attained before, it is evidence of invention."

As a result of the authorities upon this subject, it may be said that, if the new use be so nearly analogous to the former one, that the applicability of the device to its new use would occur to a person of ordinary mechanical skill, it is only a case of double use, but if the relations between them be remote, and especially if the use of the old device produce a new result, it may at least involve an exercise of the inventive faculty. Much, however, must still depend upon the nature of the changes required to adapt the device to its new use.

Applying this test to the case under consideration, it is manifest that, if the change from the glass bars of the Creager Wood Exhibit to the steel bars of the Potts cylinder was a mere change of material for the more perfect accomplishment of the same work, it would, within the familiar cases of Hotchkiss v. Greenwood, 11 How. 248; Hicks v. Kelsey, 18 Wall. 670; Terhune v. Phillips, 99 U. S. 592, and Brown v. District of Columbia, 130 U. S. 87, not involve invention. But not only did the glass bars prove so brittle in their use for polishing wood that they broke and were dis

Opinion of the Court.

carded after a half an hour's trial, but they would undoubtedly have been wholly worthless for the new use for which the Potts required them. Not only did they discard the glass bars, and substitute others of steel, but they substituted them for a purpose wholly different from that for which they had been employed. Under such circumstances, we have repeatedly held that a change of material was invention. Smith v. Goodyear Dental Vulcanite Co., 93 U. S. 486; Goodyear Dental Vulcanite Co. v. Davis, 102 U. S. 222. None of the cylinders to which our attention has been called resembled the Potts cylinder so closely as does this. None of them were used for the purpose of disintegrating, as distinguished from crushing or grinding clay. The result appears to have been a new and valuable one-so much so that, within a short time thereafter, defendants themselves obtained a patent upon a machine of their own to accomplish it. As we said in Smith v. Goodyear Dental Vulcanite Co., 93 U. S. 486, and Magowan v. New York Belting Co., 141 U. S. 332, 343, where the question of novelty is in doubt, the fact that the device has gone into general use, and displaced other devices employed for a similar purpose, is sufficient to turn the scale in favor of the invention. Our conclusion is that the patents in question are valid.

The question of infringement presents less difficulty. Defendants' machine, in its construction and operation, is substantially the same as plaintiffs'. Instead, however, of casting the shredding roller with a solid face, forming longitudinal grooves therein, and fixing the steel bars in the grooves, defendants cast the cylinder in the form of a skeleton or spider, the knives being respectively fastened to the several arms projecting from the hub, one knife to each arm, and forming the periphery by filling in metal plates between the knives. The cylinder, when its numerous parts are bolted together, is a perfect roll with a solid face, having cutting bars projecting from the slots or grooves thus formed, and adjustably secured therein by means of bolts passing through them. The operation is the same as that of the Potts machine, and it accomplishes practically the same result by practically the

same means.

VOL. CLV-39

Statement of the Case.

Defendants, in their trade circular advertising their own machine, state: "Unlike the ordinary roller process, the action of the disintegrator is to remove small portions, by cutting from the clay fed into the hopper on the same principle as shaving and whittling, and does not roll the clay into sheets, thus making it unfit for proper manipulation. The past season we have put out many of these machines in difficult clays, and made it an obligation to work the clay both wet and dry, and each machine has done its work well and to the entire satisfaction of the purchasers." This is a frank and apparently a just tribute to the merits of the plaintiffs' invention, as well as a distinct admission that their own machine accomplishes the same result.

The decree of the court below is, therefore,

Reversed and the case remanded for further proceedings in conformity with this opinion.

CAMPBELL v. HAVERHILL.

ERROR TO THE CIRCUIT COURT OF THE UNITED STATES FOR THE DISTRICT OF MASSACHUSETTS.

No. 87. Argued November 21, 22, 1894. Decided January 7, 1895.

Where a party excepts to a ruling of the court, but, not standing upon his exception, elects to proceed with the trial, he thereby waives it. The statutes of limitation of the several States apply to actions at law for the infringement of letters patent.

THIS was an action at law for the infringement of letters patent No. 42,920, issued May 24, 1864, to James Knibbs for an improvement in fire-engine pumps, of which patent plaintiffs were the assignees. The patent expired May 24, 1881. The action was begun May 20, 1887, in the name of Ruel Philbrook and several others, among whom was Christopher

Counsel for Plaintiff in Error.

C. Campbell, the plaintiff in error, claiming to be at different times assignees of the patent and of claims for infringements of the same.

Defendant pleaded among other things that "the cause of action mentioned in the plaintiffs' declaration did not occur within six years before the suing out of the plaintiffs' writ."

Upon the trial, the plaintiffs introduced evidence to show that Philbrook, by assignments, had received all the title, as assignee, held by the several assignors to him during the life. of the patent, and claimed the right to proceed in one suit in the name of all his prior assignors.

The court ruled that the action could not be maintained, and that Philbrook could not sue in the name of all the assignors, but only in the name of the party or parties who held the entire title to the patent in suit for the time being.

It was

To this ruling the plaintiff Philbrook excepted, and his exception was then and there allowed; and thereupon, by leave of the court, the plaintiff, for the purposes of that trial, discontinued as to all the plaintiffs named in the writ, except Christopher C. Campbell, and proceeded in his name. admitted for the purposes of the trial that the entire title in the patent vested in Christopher C. Campbell, individually or as trustee, from the 10th day of October, 1877, to the 20th day of December, 1880, and for the purposes of the trial no claim for damages was made in behalf of said Campbell after December 20, 1880.

The defendant then asked the court to direct a verdict for the defendant on the ground that the action was barred by the statute of limitations of the Commonwealth of Massachusetts, as all claims for action under the admission terminated December 20, 1880, and the writs were dated May 20, 1887, and were served on the 23d day of May, so that more than six years had elapsed. The court acceded to this view, decided that the Massachusetts statute of limitations was a defence to the suit, and directed a verdict for the defendant. Whereupon plaintiff Campbell sued out this writ of error.

Mr. Harvey D. Hadlock for plaintiff in error.