one entire whole, a valid claim for thus combining those elementary parts may be made."

§ 34. It is not invention to duplicate one or more of the parts of a machine.

In Dunbar v. Myers' the patent was based on a circular-saw mill adapted to sawing lumber into thin sheets to be used for the backs of picture-frames and mirrors. It differed from former machines used for the same purpose, mainly in the fact that it had a plate on each side of the saw for the purpose of expanding the saw kerf and thus keeping the sawed parts away from the sides of the saw, whereas earlier machines had such a plate on only one side of the saw. The two plates of the patented machine dif

fered from each other in diameter and in one or two other respects, but the function performed by each of them was substantially identical with that performed by the other. The Supreme Court therefore held the claim which covered the additional plate to be void for want of invention.

Millner v. Voss' was decided by Judge BOND in Virginia. The patent involved purported to cover an arrangement of furnaces and flues in a tobacco-curing house. It appeared to differ from prior arrangements only in the fact that each of the furnaces had two or more fire-places of different sizes on each side of a chimney, whereas former arrangements had but one. Judge BOND wittily said that, "Where one stove is found to be unequal to the heating of a room, to put another beside it, even though smaller, requires no invention." Mr. Millner's patent was therefore held to be void.

$35. It is not invention to omit one or more of the parts of an existing thing, unless that omission causes a new mode of operation of the parts retained.

Stow v. Chicago,' decided by Judge BLODGETT, is the case which perhaps most exactly corresponds with this rule.

1 Dunbar v. Myers, 94 U. S. 197, 1876.

2 Millner v. Voss, 4 Hughes, 262,

1882.

3 Stow v. City of Chicago, 3 Bann. & Ard. 92, 1877.

The patent in that case covered a wood pavement like that. of Nicholson, except that it omitted the board foundation. and also the board strips of that earlier pavement. Judge BLODGETT held that those omissions constituted no invention, saying: "A reconstruction of a machine, so that a less number of parts will perform all the functions of the greater, may be invention of a high order, but the omission of a part, with a corresponding omission of function, so that the retained parts do just what they did before in the combination, cannot be other than a mere matter of judgment, depending upon whether it is desirable to have the machine do all, or less, than it did before." These views were also reiterated and reinforced by the same judge many years after they were stated and applied by him in the leading case.'

The exception which is stated in the general rule of this section was judicially applied, and is well illustrated, in a case decided by Judge NATHANIEL SHIPMAN, where invention was found to reside in so reorganizing a meat-mincing machine as to dispense with many of its parts, and as to cause the parts retained to do the work of the original machine.' And in a case which involved a process patent, the Supreme Court has decided that invention resided in omitting one of the steps in an old process, where the resulting new process was the result of careful and long-continued experiment, and where its utility was decidedly greater than that of the old process.'

$36. It is not invention to improve a known structure by substituting an equivalent for either of its parts.*

What is signified in the patent law by the word "equivalent" is explained in detail in the chapter on infringement.

McClain. Ortmayer, 33 Fed. Rep. 287, 1888.

Enterprise Mfg. Co. v. Sargent, 28 Fed. Rep. 187, 1886. Lawther. Hamilton, 124 U. S. 1, 1887.

'Smith . Nichols, 21 Wallace,

119. 1874; Crouch v. Roemer, 103 U. S. 797, 1880; Cochrane v. Waterman, 1 McArthur's Patent Cases, 54, 1844; Perry v. Foundry Co. 12 Fed Rep. 436, 1882; Celluloid Mfg. Co. v. Tower, 26 Fed. Rep. 451, 1885.

The subject is of double importance, because it relates sometimes to the validity and sometimes to the infringement of patents. A. B. may construct and may patent a machine which differs from the prior patented machine of C. D. in one part only. If the courts decide that the new part inserted, is an equivalent of the old part omitted, then the machine of A. B. will be an infringement; and it will not be an invention, unless the new part, not only performs the function of the part for which it was substituted, but also performs another function by another mode of operation.' If, on the other hand, the courts hold that the part inserted is not an equivalent of the old part omitted, then the machine of A. B. may be an invention, and it will not be an infringement of any claim covering the entire machine of C. D.

$37. It is not invention to combine old devices into a new article without producing any new mode of operation.

Stimpson v. Woodman' involved a patent for a machine for pebbling leather. It gave the leather the pebbled surface by means of a roller, which had the counterpart of that surface engraved or sunk on its periphery. The same kind of roller had previously been used for the same purpose by hand, and the same kind of machine had been used for compressing leather, except that the roller in it was smooth. The Supreme Court held that the change involved in putting the old figured hand roller in the place of the plain roller of the machine, involved no invention, and that the patent was void, if the facts were as stated.

Heald v. Rice' was based on a patent which covered a certain previously known straw-feeding attachment in combination with a certain previously known return-flue boiler, that straw-feeding attachment having been previously combined with a fire-box boiler. The utility of the return-flue boiler in that combination was much greater than that of

the fire-box boiler, but the Supreme Court nevertheless held that there was no invention in the union of the former with the straw-feeding attachment.

Hall v. Macneale' shows the following state of facts. The patentee first made safe doors the plates of which were held together by cored conical arbors, having screw threads cut on their exterior surfaces, and later he made other safe doors the plates of which were held together by solid conical arbors which had no such screw threads as the cored conical arbors had, and he afterward obtained a patent for the combination of the plates of safe doors with solid conical arbors having such screw threads. The Supreme Court, speaking by Justice BLATCHFORD, said that "There was no invention in adding to the solid conical bolt the screw thread of the cored conical bolt."

Many Circuit Court cases also involve the doctrine of this section. In one such case Justice BLATCHFORD held a patent to be void for want of invention which covered a combination of a whip socket having an annular recess in it, with a flexible elastic ring held in that recess by its own elasticity, and provided on its inner edge with non-contiguous projections, separated so that they could not be pressed into contact with each other by the insertion of the whip handle into the ring. That decision was based on the fact that a prior whip socket having an annular recess had been combined with a plain rubber ring in that recess, and on the further fact that flexible elastic rings constructed like those of the patent had been combined with a whip socket which had no annular recess, but which clamped that ring between the upper end of that socket and a cap above it. Judge LOWELL has also decided three similar cases. In one of them' he held it to be no invention to give paper collars the same kind of surface that had theretofore been impressed upon other articles of paper. In

'Hall v. Macneale, 107 U. S. 90, 1882.

Searls. Merriam, 22 Off. Gaz.

1040, 1882.

Union Paper Collar Co. v. Leland, 1 Bann. & Ard. 491, 1874.

another' he decided that, embossed lines on writing-paper being old, and ogee lines embossed on other paper being old, there was no invention in embossing ogee lines on writing-paper, to serve as guides to the eye of the writer. In a third case,' he held that, soft base-balls having been covered with a double cover, and hard base-balls having been covered with a single cover, there was no invention in covering a hard base-ball with a double cover. And other still later cases illustrate the same doctrine.'

§ 38. It is not invention to use an old thing or process. for a new purpose.

4

In Tucker v. Spalding the patent covered a combination of a circular disk with removable saw teeth. There was

a prior combination of a circular disk with removable cutters for the purpose of cutting tongues and grooves. The Supreme Court held that if what the latter combination did was in its nature the same as sawing, and if its structure and its action suggested to the mind of the ordinarily skilful mechanic this double use to which it could be adapted without material change, then the combination of the patent was but a double use of the older combination, and was therefore not an invention, and not patentable.

Brown v. Piper' is a case in which the Supreme Court held, that a patent for an apparatus for preserving fish and other articles in a close chamber by means of a freezingmixture having no contact with the atmosphere of the preserving chamber, covered nothing but a double use of the well-known ice-cream freezer.

6

In Roberts v. Ryer the same tribunal decided that to

1 Cone v. Morgan Envelope Co. 4 Bann. & Ard. 109, 1879.

Mahn v. Harwood, 3 Bann. & Ard. 517, 1878.

3 Yale Lock Mfg. Co. v. National Bank, 17 Fed. Rep. 533, 1883; Kaaps v. Hartung, 23 Fed. Rep. 187, 1885; Troy Machinery Co. v. Bunnell, 27 Fed. Rep. 810, 1886; Union Edge Setter Co. v. Keith, 31 Fed. Rep. 46,

1887; Washburn & Moen Mfg. Co. v. Barbed Wire Co. 33 Fed. Rep. 273, 1888; Low v. Stove Co. 36 Fed. Rep. 903, 1888.

4 Tucker v. Spalding, 13 Wallace, 453, 1871.

Brown v. Piper, 91 U. S. 37,

1875.

Roberts v. Ryer, 91 U. S. 157,

1875.