light, and inconspicuous. As a branch connection at the junction between such conductors, it is efficient, and its value has been generally recognized. The ordinary track frog, as a structural device, has only a remote resemblance to it. The suggestion that it could be utilized in an overhead line wire junction would seem ludicrous, and it could only be done by denuding it of its most conspicuous characteristics. Various expedients for switching with such conductors have been resorted to by experts in the art. The fact that they overlooked devices like the patented device, and resorted to clumsy or inconvenient means, cannot be ignored. It was not a great invention, but that it was an invention requiring a degree of ingenuity somewhat beyond the ordinary skill of the calling we are unable to doubt.

There are two other claims in the patent which relate specifically to the conductor switch. These are as follows:

“(9) In an electric railway, a switching device for suspended conductors, comprising two or more branching compartments or ways corresponding to the direction of the track, and of the main and branch conductors, and secured to the said suspended conductors, substantially as described.

"(10) In an electric railway, a switching device for suspended conductors, consisting of an open-bottom box formed with two or more branching compartments corresponding to the direction of the track, and arranged to be secured to the conductor, substantially as described."

The observations which have been made with respect to claim 2 apply equally to these claims. We think they are destitute of patentable novelty.

Another group of claims are those relating to the trailing trolley and relative arrangement of trolley switches and branch switches. Those in controversy are as follows:

"(4) The combination of a track having switches, an overhead conductor above the track and having switches, and a car on the track provided with a contact-carrying arm arranged to engage the conductor at a point in rear of the front wheels of the car."

"(20) In an electric railway, the combination, with an overhead switchplate having depending ribs, but open at its extremities, of main and branch conductors extending from its two extremities, respectively, a vehicle, an upwardly pressed contact arm attached to the vehicle, and tending to move laterally therewith, and a track switch for the vehicle, located so as to operate in advance of the conductor switch."

"(23) The combination, with branching overhead conductors, of a vehicle having a laterally swinging contact arm pressed upward to engage the conductors, and a switch plate at the branching point having depending sides, but open at its extremities, the interior width of the plate between the sides being greater than the thickness of the contact wheel, whereby the wheel is free to move laterally with relation to the main conductor, and engage one of the branching conductors."

“(25) In a branching electric railway, the combination of a track switch, an overhead conductor switch, and a vehicle having a rearwardly extending contact arm, whereby the track switch will operate in advance of the conductor switch.

"(26) In a branching electric railway, the combination, with a vehicle, of a track switch, an overhead conductor switch, and a contact arm extending upward from the vehicle to the conductor, and so located relatively to the length of the vehicle and the two switches that the lateral movement of the vehicle will give a corresponding movement of the contact device on the conductor switch.

v.71F.no.3-26

“(27) In a branching electric railway, the combination, with a vehicle, of a track switch, a contact device consisting of a trailing, spring-pressed arm, having a grooved contact piece embracing the conductor, and guided thereby, the said arm being jointed to the car, and tending to move laterally therewith, and an overhead conductor switch adapted to engage the contact piece, and whereby the extremity of the arm is flexibly guided from main to branch conductor."

The arrangement of the track switch in such relation to the conductor switch and the interposed trolley that the movement of the forward part of the car upon the branch track will deflect the trolley wheel, and guide it naturally into the proper compartment of the conductor switch, is an important feature of the invention. It effects such a co-operation of the parts as to utilize the initial lateral movement of the car itself as the means for determining the directive action of the conductor switch, and thus renders the switching operation an automatic one. The description necessarily calls for the location of the track switch somewhat in advance of the conductor switch, or of the trolley, so as to engage the conductor in rear of the forward part of the car, sufficiently so as to impart the necessary directive action to the trolley wheel as it enters the conductor switch. The value of this simple arrangement, by which the manipulation of the trolley by an attendant upon the cars is no longer necessary, is obvious. It has been universally adopted, and has required no improvement since its introduction into electric railways. These facts sufficiently attest the patentable novelty of the invention of the claims.

Claims 32 and 33 of the patent relate to the centralizing spring which controls the lateral movement of the trailing trolley arm. This division of the invention is described in the specification as follows:

"E is the traveling contact wheel, and F is a hinged arm supported upon a post, f, secured to, or extending upward from, the roof of the car. To the lower end of the arm, F, is attached a spring, G, to the lower extremity of which is secured a cord, which passes downward through suitable grooves, or over suitable rollers, and is provided with a weight, H, which serves to hold the spring down and keep the contact wheel, E, always pressed up against the under side of the conductor, D. At the same time the spring will instantly yield to allow the wheel to pass under the switch or any obstruction, and while the arm, F, is movable laterally with respect to the vehicle, the spring and weight will constantly tend to restore the arm to its normal central position, and assist in causing the contact arm to partake of the lateral movement of the vehicle."

The claims are as follows:

"(32) In an electric railway, the combination, with an overhead conductor and a vehicle, of a trailing contact arm guided at its outer end by the overhead conductor, and movable laterally relatively to the vehicle, but having a normal centralizing tendency by means of a spring or weight.

"(33) In an electric railway, the combination, with an overhead conductor and a vehicle, of an intermediate contact device consisting of an upwardly pressed trailing arm having a grooved contact wheel at its outer end, by which it is guided by the conductor; the said arm being free to swing laterally relatively to the vehicle, but tending to remain in its normal central position by means of a spring or weight."

It is not contended for the defendant that these claims do not cover patentable inventions.

Another group of claims are those relating to the combination of the pivoted trolley arm, and its weight and spring mechanism.' These claims are founded upon the extract from the specification just quoted, and are as follows:

"(15) In an electric railway, the combination of a car, a conductor suspended above the line of travel of the car, a contact-carrying arm pivotally supported on top of the car, and provided at its outer end with a contact roller engaging the under side of the suspended conductor, and a weighted spring at or near the inner end of the arm for maintaining said upward contact, substantially as described.

“(16) In an electric railway, the combination of a car provided with a pivoted arm, as F, having a contact at its outer extremity, a tension spring, as G, attached at its inner extremity, and a vertically moving weight connected to said spring for holding the same in operative relation to the arm throughout its entire range of movement, substantially as described. "(17) In an electric railway, the combination of the car having suitably pivoted arm, F, carrying a contact wheel at its outer extremity, a spring, G, secured to its lower extremity, and a connection extending from said spring, and provided with a weight at its lower end, substantially as described."

The court below held that these claims were not infringed, and that part of the decree is the subject of the appeal by the complainant. We think the conclusion of the court below was plainly right. Judge Coxe said:

"One of the elements of the claims is a 'weighted spring,' or, as it is expressed in claim 16, 'a vertical moving weight connected to said spring,' and in claim 17 'a connection extending from said spring, and provided with a weight at its lower end.' The function of the 'weight, H,' is pointed out with care in the description. Defendant does not use this weight in any manner whatever, and consequently does not infringe."

It is the function of the weight to hold the spring down, and give to the contact wheel a greater range of action. The claims are too explicit to be altered or enlarged by the omission of the weight. The spring itself could as reasonably be eliminated as the weight.

It is insisted for the defendant that the claims which we have thus far concluded to be valid, and to have been infringed, are void because their inventions were previously patented by the same inventor.

The only patents of Van Depoele which preceded the patent in suit, and which describe and illustrate devices of the same general character, are six in number, viz.: No. 394,039, dated December 4, 1888; No. 397,451, dated February 5, 1889; No. 402,117, dated April 23, 1889; No. 408,638, dated August 6, 1889; No. 409,156, dated August 13, 1889; No. 424,380, dated March 25, 1890. All of these patents were granted to him while the application for the patent in suit was pending in the patent office, and on applications which were filed after the date of the original application for the patent in suit.

In the argument at the bar, No. 397,451 has been treated as the most important of these patents. The testimony of the expert witness for the defendant was exclusively confined to an analysis of that patent. It is relied upon to defeat the switch-plate claims, and the claims relating to the centralizing spring. It does not affect the claims relating to the directive action of the switch track, nor, so'

far as we are able to discover, in the absence of any expert testimony in regard to them, do any of the others of the preceding patents. The considerations which will control the effect of No. 397,451 are equally pertinent to the other patents. For these reasons it will not be nec

essary or profitable to consider them.

Upon cross-examination the expert for the defendant testified as follows:

"Question. I notice that in referring to Van Depoele's earlier patent, No. 397,451, in connection with the various claims of the patent in suit, you have been quite careful to say that you find the combinations of the several claims of the patent in suit 'shown and described in the earlier patent.' You have nowhere said, I believe, that you find any one of the combinations covered by the claims of the patent in suit to have been claimed in the earlier patent. Do you, in fact, find any one of these combinations to have been claimed in patent 397,451; and, if so, please indicate what one, or, if more than one, what ones?

"Answer. I do not think any of the combinations that are claimed in 424,695 are also claimed as such in 397,451. Patent 397,451 contains apparently limited claims, while patent 424,695 contains broader claims, or claims which are less restricted than the claims of the earlier patent.

"Question. Do you find in the earlier patent, No. 397,451, any claims which would necessarily include the apparatus or the construction which is shown and described in the patent in suit, No. 424.695?

"Answer. The situation is the reverse, as I understand it. The claims of 424,695 include the apparatus shown in patent 397,451, but the claims of 397,451 do not cover the devices of 424,695."

This evidence was not objected to, and is recited merely because it is a plain and concise statement of the opinion of the expert as to the true scope of the claims of the two patents.

The argument for the defendant is that the patent in suit merely claims the matter of the earlier patent more generically, or in broader terms; that it selects and withdraws fundamental parts of the combinations claimed in the earlier patent, without which those combinations could not exist, and patents them again; and that the inventions, because inseparably involved in the patented matter of the earlier patent, are covered by it.

The principles of law applicable to the case may be briefly stated. An inventor, by describing an invention in a patent granted to him, does not necessarily preclude himself from patenting it subsequently. His omission to claim what he describes may operate as a disclaimer or an abandonment of the matter not claimed; but it has no such effect when it appears that the matter thus described, but not claimed, was the subject of a pending application in the patent office by him for another patent. This was explicitly adjudged in Suffolk Co. v. Hayden, 3 Wall. 315, and recognized as sound doctrine in the BarbedWire Case, 143 U. S. 275, 12 Sup. Ct. 443, 450. The invention secured by a patent is that which is secured to the patentee by the claim. The claim is a statutory requirement prescribed for the purpose of making a patentee define what his intention is so distinctly and exactly as to apprise other inventors, and the public, what is withdrawn from general use. The claim, however, is to be read in the light of the description contained in the specification, and its literal terms may be enlarged or narrowed accordingly, but not to an extent inconsistent with their meaning. Identity of language in the claims of

two patents does not necessarily import that the invention patented by each is identical, nor does a difference in phraseology necessarily import that they are for different inventions. The test of identity is whether both, when properly construed in the light of the description, define essentially the same thing. When the claims of both cover and control essentially the same subject-matter, both are for the same invention, and the later patent is void.

A machine or structure may embody several different inventions. There may be subcombinations in a machine which are new and useful, and operate conjointly to perform some subordinate function. Such a subcombination, if not patented by a claim, might be appropriated by another without infringing a patent for the machine. Being for a different invention, it is the proper subject of a distinct patent. While two or more inventions residing in the same combination or structure may be covered by a corresponding number of claims in a single patent, the law does not require them all to be claimed. in the same patent, and the inventions may, at the option of the patentee, be secured by different patents. It is quite immaterial that both inventions originate at the same time, and from a single conception. In Cochrane v. Deener, 94 U. S. 780, the court said, "One invention may include within it many others, and each and all may be valid at the same time." In all such cases, if the inventions are truly separable, the inventor is entitled to a monopoly for it, although neither could have been discovered and made available without the other. The invention of a new art, machine, or manufacture, and the invention of an improvement upon either, are substantially distinct and separate; and because this is so the order of priority between patents to the same inventor for the different inventions, in the absence of abandonment or disclaimer, is immaterial. These various propositions may be summed up by adopting the language of the court in Miller v. Manufacturing Co., 151 U. S. 198, 14 Sup. Ct. 310: "The result of the foregoing and other authorities is that no patent can issue for an invention actually covered by a former patent, especially to the same patentee, although the terms of the claims may differ; that the second patent, although containing a broader claim, more generical in its character than the specific claims contained in the prior patent, is also void; but that where the second patent covers matter described in the prior patent, essentially distinct and separable from the invention covered thereby and claims made thereunder, its validity may be sustained. In the last class of cases it must distinctly appear that the invention covered by the later patent was a separate invention, distinctly different and independent from that covered by the first patent; in other words, it must be something substantially different from that comprehended in the first patent. It must consist in something more than a mere distinction of the breadth or scope of the claims of each patent."

Some observations in Miller v. Manufacturing Co. seem to have created some misapprehension of the scope of that decision on the part of the profession, but the principles enunciated in the opinion are so plainly stated that those observations, when considered in their application to the case before the court, ought not to be misconceived. The court decided in that case that the two patents to Wright were in fact for the same invention, and consequently the later patent was void. The invention of Wright, and his only in