after stating the facts, delivered the opinion:
Claim No. 6 may be taken as a single comprehensive statement of the invention claimed. That claim is as follows:
6. The combination with a telephone line, of a relay responding to currents in the line, a local circuit including a source of current, a resistance-coil, and a line-signal lamp, controlled by the relay, the line-signal being associated with a spring-jack of the line, a connecting plug for use with the spring-jack, a clearing-out-signal lamp associated with the connecting-plug, and switch-contacts adapted to close a shunt-circuit through the clearing-out-signal lamp about the line-signal lamp and the contact-points of the relay when the plug is inserted into the spring-jack, substantially as described.
This claim when applied to the art shows a combination within a con■ bination, with means connecting the inner with the greater; and it is essential, in determining the scope of the patent, to keep in mind as separate entities, this greater combination, this inner combination, and the specific means that connect them.
The greater combination is the telephone line, fully equipped with the signaling system described.
*693The inner combination is the signaling system — -two signal lamps so placed in parallel branches of a local circuit, that when either branch is open, the lamp on the other will be luminous, and therefore a signal, but when both branches are closed, both lamps will be “effaced,” and therefore neither a signal; this concept being mechanically embodied in the line lamp associated with a spring jack of the line, the connecting plug for use with the spring jack, the supervisory lamp associated with the connecting plug, the switch contacts, and the resistance coil controlling the flow to the lamps.
The means connecting the inner combination with the greater combination is the relay responding to currents in the main line, whereby the local circuit is connected electrically with the main line.
We see no invention in the mere selection of this connecting means —the connecting of the inner combination with the greater combination by means of the relay — relays to put electric lamps on local circuits into connection with the main lines of electric lighting systems being in common use.
We see no invention in the mere selection, as signals, of electric lamps. The electric lamp, in the patent sense, is as old as sunlight. So also the placing of two or more lamps upon parallel branches of the same circuit. We do not think that the mere adaptation to a telephone line of electric lamps as signals — apart from the special concept that the lamps should be so balanced, that on a massed current each lamp would be luminous, while on a divided current both would be non-luminous, and the mechanical embodiment of that concept — is patentable invention. The only new element, therefore, in the combination patented, is the concept named, together with the mechanical means in which it is embodied. But here again, when we come to look at the prior art, there must be a further elimination.
That concept, to repeat what has been said before, is the so placing of two signal lamps in parallel branches of the same circuit, that when either branch is open, the lamp on the other will be luminous, but when both branches are closed, neither will be practically luminous —a concept proceeding upon this thought, that a current might be so predetermined or pitched, that going through one of two lamps of identical character it would be sufficient to make that lamp practically luminous, but being divided in equal parts, between the two lamps, it would be so insufficient that neither lamp, practically, would be luminous.
Now, except for this specific concept of the difference of effect uj)on identical lamps of a current massed, and a current divided, and the adaptation to its purpose of an otherwise old mechanical dress, the whole mechanism of the patent in suit is old — being fully set forth in Scribner’s patent, No. .'>59,(51 {>, issued five years previously. In this earlier patent Scribner combined with a telephone line, indicator signals. The combination embodied a source of current, a resistance coil, a line signal associated with the spring jack on the line, a connecting plug for use with the spring jack, a supervisory signal associated with the connecting plug and switch contacts, all similar to *694those in the patent in suit. The earlier patent included, also, the closing of the two circuits on which the signals were located, at the same time and to.the same .current of electricity, whereby, theoretically at least, the current was divided. There is, however, this difference, that whereas in the patent in suit each lamp presents an equal resistance, whereby the current approximately is equally, divided, in the earlier patent the signals present differing resistance so that, though the current may have traveled in differing voltage through both signals, the smaller current was so small that the signal placed upon it did not operate. Indeed, while Scribner, in the earlier patent, may not have contributed to electrical knowledge the exact concept embodied in the'inner combination of the patent in suit, he did contribute there the thought that led up to his later ■ thought; and, what is certainly to the point, the precise mechanism, save as such mechanism is modified by the substitution of electric lamps for indicator signals, and save also that for signals presenting differing resistances, he substituted, in the later patent, signals of identical resistance.
Here, then (considering that the mere choice of lamps as signals is not patentably a new thing), is the only element of the patent in suit not found in the previous art: Identity of signal lamps, and an exact predetermined pitch of current, the identity of the lamps being essential because any difference of resistance would break the fine balancing of current upon which the whole conception rests; and a predetermined pitch of current, neither too high nor too low, being essential, because, a current pitched too high, though it might make the lamps more luminous, would not, when divided, efface the lamps, while a current pitched too low, while when divided making the effacement more complete, would not, when massed, give sufficient luminosity.
The new element thus bounded and identified must not be lost sight of; for unless it is found substantially in appellees’ device, the combination constituting appellees’ device cannot be held to be an infringement.
The patent in suit, based on this element, had its defects. Theoretically, an equal division of current "cuts such current into halves. But practically, the current being divided, the resistance is so diminished that each line of the divided circuit gets considerably more than one-half of the current massed. The effect of this is, that there is not such a wide difference between the luminosity of the lamp fed by the current massed and the current divided, as the inventor perhaps anticipated; so that, accessory to making the signals practical, these three things at least were added: The lamp was covered with a lense, not solely for. radiating the light, but to partially smother it; the uniformity of the lamps had to be maintained — that is, the lamps not only had to be uniform when put in, but replaced the moment that, through use, a difference in uniformity developed; and the batteries had to be kept at a given voltage — a variation of voltage or diminution of the flow, destroying the fine balance upon which alone the luminosity and non-luminosity of the lamps are maintained.
*695That these defects were actual is shown by the fact that the patent in suit has not gone into general use. They are apparent in the exchange at Worcester, Mass. Of this exchange McBerty, one of appellant’s witnesses says:
“The voltage is kept nearly constant. In order to accomplish this, duplicate sets of battery are provided, one of -which is charged while the other is being used. When a lamp is discovered in a switchboard which grows somewhat red because of high resistance, it is replaced by a normal lamp. At midday when the sunlight is strong, a translucent shade is drawn over the skylight.”
Again he says:
“I very early became aware of the difficulty in producing uniform lamps, and of maintaining uniformity in the -battery voltages. I also studied other ways of accomplishing the same result, without the addition of mechanism and circuits. One way consisted in putting a filament of green gelatin, or glass, behind the opal. This filament obstructed the red light emanating from the dull growing filament, while it did not obstruct the white light of the filament when fully illuminated.”
It was, we believe, just to avoid these defects — to give to the signaling more robustness — that electrical thought went on thinking and experimenting, developing, among other tilings, the system used by the appellee.
That system is connected to the general telephone line by means of the relay, just as appellant’s system is. But this does not make it an infringement; for, as already indicated, the mere insertion of such signaling system into a general telephone line, and the means by which that insertion is brought about, were, in the field of electric mechanics, as shown by the previous art, so obvious, that they constitute separately, no part of whatever was patentable in the patent in suit.
The appellee’s system employs the device of a signaling lamp associated with a supervisory lamp, each being on a circuit alone at times, and both being upon a circuit together at times, with the result; that when each is on the circuit alone it is a signal, but when both are on the circuit at once, neither are signals; together with the resistance coils, spring jacks, connecting plugs and the like, that mechanically bring this about. But this device, save that the association is on the main line, instead of a local circuit connectable, when signaling is needed, with the main line, and save also that the signal is an indicator instead of a lamp, is present, in all substantial respects, in patent No. ñi)9,6.16; and as already stated, the mere substitution of an electric light for an indicator, and the mere placing of the signaling device on a local, instead of the main line, do not constitute patentable invention. But even if they did, it would be of no consequence in this suit, unless the inner element — the so placing of the lamps that they followed the law of the patentee’s conception — is to be found substantially in appellee’s combination. And that brings us to the system used by appellee.
*696The following diagrams show the appellee’s system (1) in normal condition; (2) subscriber calling; (3) conversation taking place, and (4) disconnecting signal:
When the subscriber in appellee’s system removes his telephone from its hook, the calling relay i attracting the armature k" closes the circuit from the battery through the resistance coil e, and the signal lamp n as shown by the heavy lines. The whole current being through n, the lamp lights up and becomes the signal..
The operator now inserts the plug into the corresponding spring jack, thus closing the plug contact. Now the circuit being divided, if the lamps were of equal resistance, the current would be divided, as in the patent in suit, both lamps becoming partially non-luminous. But in appellee’s system, appellee’s lamp v, interposing very much less resistance than lamp n, and the current taking the path of least resistance, the current practically passes almost altogether through lamp v, according to the heavy lines in Figure 3; leaving a small portion, if-any, to pass through lamp n, and thus electrically short circuiting n, just as signal h in patent No. 559,616, is electrically short circuited by interposing in the path of the current a resistance higher than that through signal e.
This diversion of current through v does not light the lamp, however, because v being a lamp of different character from n, it requires a voltage greater than the whole voltage of the current when subjected to the resistance e, the supervisory lamp in both cases considered and be in circuit. So the circuit through the resistance coil g is introduced, closed by the subscriber replacing his telephone; and g interposing a less resistance than e, a voltage enough greater than the voltage through e alone is obtained that 'the lamp v is lighted.
Now compare this with what we have found to be the actual con*697cept of the ¡latent in suit. The patent in suit employs a single predetermined pitch of current, as it reaches the lamps through resistance m, and would operate under no other conditions; the appellees’ system carries a current varying according to the lamps to be lighted, and would operate under no other conditions. The patent in suit provides for extinguishment by an approximately equal division of the current, and looks in pursuit of this purpose to no other provision; the appellees’ system provides for extinguishment of the line lamp by practically short circuiting, and the supervisory lamp by a high candle power, and would operate in no other way. The patent in suit involves the necessity of lamps of identical character — lamps so delicately matched that in dividing the current, the flow through each lamp will be. equal — and the patent in suit would operate under no other conditions; the appellee’s system employs lamps so differing from each other in character, that any.close balancing of the lamps is a matter that is not involved. In the patent in suit, the current must be pitched to almost an exact predetermined point — involving battcrj . action constantly up to a certain point, and a resistance that is constant; the operation of appellee’s system cannot be said to hinge in the least, upon pitch of current. When we have thus passed over all that is old in the art, reaching the actual concept covered by the patent in suit, the differences pointed out become fundamental. They mark two substantially differing lines of thought. And they have resulted in two distinct signaling systems, in the one of which the defects in the other have been escaped chiefly by avoiding all in it that was new, while readaptiug certain things in it that were old. This, in our judgment, differentiates the essential element under consideration in appellee’s device, from the element that gives to the patent in suit any patentable invention, if indeed, it have any patentable invention; wherefore it follows that the one combination is not an infringement upon the other.
The audible test being governed by the same considerations, heed not be further discussed'.
The decree of the Circuit Court is affirmed.