compound watch key seems simple and obvious enough after its invention; if it had been both before its invention, it would undoubtedly have been produced as soon as watches were made with winding stems of different sizes.

Again, in the early stage of the manufacture of cut nails in this country, tapering slips of iron were cut successively from a piece of nail plate by a machine having knives or cutters operated by power. These slips were picked up by an operator and presented one at a time to a second machine by which they were gripped near the larger end, and the larger extremity projecting beyond the grippers was compressed endwise or, technically speaking, upset, to form the head of the nail. As the two machines stood side by side, they constituted an aggregation, it being immaterial whether or not one worked at identically the same speed as the other. An ingenious mechanic put together those members of the two machines which acted directly upon the material, and connected them with one driving shaft so that they operated in concert and so that the slip cut by the cutting devices passed directly to the grippers and heading tool, all secured and operated in the same frame. The same devices performed precisely the same functions as they did in the two distinct machines, and so far as the product was concerned (the complete nail) there was no new result. But when the devices were put together in one machine, two things had to be done; first, to conceive mentally that the devices could be combined and in what manner; second, to combine them mechanically by a frame so that they were held in their proper relative positions for operation, and to combine them also with the same driving shaft (through intervening power

transmitting devices) so that their several operations were properly timed and that the grippers and header were in the proper positions to receive the cut slip when it was delivered by the knives or cutters; in other words to combine them so that the several acting devices would operate in concert. The new machine thus produced had a new collective mode of operation, which as a whole did not exist in either of earlier two machines, viz: it cut, gripped, and headed, and performed these three operations consecutively and in concert. This result was a new mode of operation, although the resulting product (the nail) was old; and the new machine was, in the estimation of a mechanic, a true and patentable combination, notwithstanding the fact that the action of the cutting members or devices was not affected or changed by the addition of the grippers and header, or that the action of the last two was neither affected nor changed by the addition of the first.

§ 44. Conditions under which a Combination Exists.

The foregoing instances show that a mechanical combination exists when two or more devices are connected, so that one sustains the other in doing its work or performing its function, even though neither moves when operating; also, when two or more devices are so connected that the result of the connection is a duplex or multiplex mode of operation, and that the combination as a whole has a duplex or multiplex capacity or property; also, when two or more devices are so connected in one machine or implement that it has a new collective mode of operation, although the said devices operate separately and successively, and although neither affects the peculiar function of the other or acts upon

the article at the same moment with the other to produce the result by simultaneous joint action; also when two or more devices are so connected in one machine as to operate successively in concert to produce a result which is due to their successive concerted actions; as well as when, as in the case of the saw mill referred to in § 42, two or more devices are connected in one machine so as to operate simultaneously to produce a result which is due to their simultaneous joint action. The examples

also show that the result attained is not necessarily the production of a new article, but is frequently the new collective mode of operation effected in producing an old article, or in accomplishing an old purpose.

§ 45. Patentable Combinations.

In order that the combination may be patentable it should not fall within any one of the exceptions mentioned in § 6, ante; and there is no objection to the requirement that the result of the combination shall be new, provided the real result be considered. Thus in the case of the illustration of the stem-winding watch set forth as a patentable combination by the Supreme Court, that court conceded that there was a new and double or duplex effect or result, the same stem performing two distinct duties which were not performed simultaneously; but, while precisely the same kind of double or duplex effect or result was performed by the single handle or holder in the compound pencil combination, the court was unable to perceive the fact. And it is often the case that the real result is not appreciated. Take the case of a cart from which the axle-tree and wheels have been removed, we may say that the result of its use in that condition is to hold articles and

to enable them to be moved by a horse; add the axle and wheels and we may say that the result is the same as before, because in both cases the cart body will hold articles and the shafts enable the articles so held to be moved by a horse. This conclusion as to the result in the last case is mechanically unsound, because it comprises only a part of the real result of the cart with wheels, as compared with the combination of a cart body and shafts without wheels; the real result of the former being not only to hold the articles and enable them to be moved by a horse, but also to enable the articles to be held and moved with greatly reduced friction and force. In like manner the real result in a compound tool is its duplex or multiplex capacity; and it often happens that when the product of a machine is an old result in product, there is, nevertheless, a new result consisting in a new mode of operation, either collective or collective and joint, by which that old product is produced.

§ 46. Substitutions in Old Combinations Patentable.

In the progress of invention many primary or generic combinations have been devised for performing useful operations, and many improvements upon such primary combinations have been made in which one or more of the devices of the primary combinations have been replaced by others of the same genera but of different species. It is a common defense in suits under patents for such secondary or specific combinations, as they may be termed, to contend that the substituted devices are mere equivalents or substitutes for those which they have replaced in the primary or generic combination, and that, therefore, the secondary combination of species

which have never before been combined is not an invention. If, however, we test the case by the principles previously laid down it is easy to decide whether the change is a mere substitution of one well known device for another, or amounts to an invention which is patentable.

As an illustration of such a case of specific combinations amounting to invention, we have the Earle shingle mill with the circular saw previously referred to. § 15. We have another illustration in the Crompton loom for fancy weaving (patent dated November 24, 1837; subsequently extended, and reissued September 13, 1853). The new combination produced by Crompton was composed of four devices called respectively the pattern cylinder, the series of double hooked jacks, the lifter, and the depressor. The jacks were upright bars connected with the leaves of heddles by which the warp threads were put into their proper relative positions for the passage of the shuttle, or technically the shed was opened for that passage; some of the warp threads being raised above a mean line by the depression of the proper jacks while others were lowered or drawn down from the same line by the lifting of others of the jacks. Each jack was constructed with two hooks in reversed positions, one near each end of the jack. The lifter and the depressor were horizontal bars arranged crosswise of the jacks, and they had reciprocating rising and descending motions imparted to them, preceding each throw of the shuttle. Hence, if the upper hook or hooks of any one or more jacks were held within the range of movement of the lifter, it or they were raised; and if, at the same time, the lower hook or hooks of any other one or more jacks were held within the range of movement of