[1] The nature of the evidence produced, and method of presentation, has produced a somewhat misleading resemblance between this suit and the ordinary proceeding for infringement. It must, however, he recognized that the usual infringement suit is to restrain a continuing tort, while this is upon a contract, under which defendant is a licensee. Therefore it is admittedly estopped to deny validity, and bound to accord to plaintiff a benevolent interpretation of the patents under which license exists. This last statement is really but a corollary to the rule that invention is part of validity, and the obligation to admit invention practically limits the evidential *396value of such prior art as may exist. With the foregoing admitted — • and it has not been denied in argument — we perceive no question of law in this record. The thing said by plaintiff to “operate in accordance with” the claims above enumerated, is used as a relay in what is just at present the longest of long-distance telephony.
Defendant yields tribute to De Forest 841,387 (claims 4 and 6), and. we are convinced that this relay is in fact a descendant of the “three-member device” there revealed by that patentee.1 The relay shows an in-put circuit connected with the filament and grid, and an out-put with the filament and plate. The filament is independently heated, and both filament and plate as used by defendant and others, are older than the inventions of either De Forest or Hewitt.
“Grid” is a word perhaps coined by that well-known phrasemaker, De Forest; at all events it is called throughout this record the De Forest grid. Filament, plate, and grid are in practice inclosed in an evacuated tube exhausted to a pressure of the order of one hundred-thou-' sandth of a millimeter. . That pressure can be still further reduced, but such reduction is expensive and does not change or improve the working of the apparatus. The normal operation of this audion amplifier, with the grid located between filame'nt and plate, is, according to the electronic theory, that a current consisting of negative carriers tends to pass from filament to plate because they, being negative, are attracted to the plate, which is positive. The rate of passage, and therefore the amount of current flowing, will depend upon how forcibly the positive plate attracts, and that depends upon the intensity of the electrical field acting in the space between plate and filament.
The grid acts (as testified by plaintiff’s expert, and imitating Hewitt’s specification language) as a capacity charged to a potential rather than as a current flowing; but, be that as it may, it is asserted by defendants that the transmitter on the in-put varies the potential impressed upon the grid, and the grid in turn similarly varies the electrical -field between filament and plate wherein said grid is commonly located. Therefore the tendency of the negative carriers to pass from filament to plate increases or decreases according to th,e fluctuating of grid potential, and similarly varies the current flowing across said electrical field and into the out-put. The result as claimed by defendant is that “the action is due solely to the De Forest grid,” and when the elements of the audion amplifier are properly (and from the evidence apparently empirically) .proportioned and co-related, repetition and amplification take place without distortion, but always the work is said by defendant to be done by the properly placed and proportioned grid.
Plaintiff’s contention may be summarily stated thus: (a) It is not the grid per se that does the work or accomplishes.the result; for the nature of an atmospheric residuum in even so highly evacuated a tube as that of defendant either has something to do with it or produces a condition answering to the “vapor” of Hewitt’s patents; but anyhow (b) the De Forest grid, if not in its original conception, at all events in re*397spect of its use by defendant, is the Hewitt shield of the later patents above mentioned.
Much of this record is occupied .with evidence pro and con as to whether the theory of operation advanced in the disclosures of 781,001 and 781,002 is not wholly erroneous; whether the devices there suggested are of any practical use; whether they constituted any real advance upon the prior art; and whether defendant did or did not utilize them, or either of them, in the construction of a mercury vapor amplifier which was made — allegedly under other patents of Hewitt not here involved, and on which plaintiff received royalties. We do not find it necessary to discuss this evidence, but prefer tO'ground decision as to the earlier patents on one proposition only.
[2] Plaintiff (or his counsel for him) contends that a vapor tube, a vacuum bulb, and an evacuated container all mean practically the same tiling for the purposes of this case. He admits that when these patents were applied for, he was thinking in terms of those mercury tubes which have made him famous. But it was then true, and always will be true, that, as long as there is any residual air left in an evacuated container, that container incloses a vapor. Therefore it is as much a vapor tube for the purposes of the present discussion as if it were filled at a fairly high pressure with any of the numerous gases suggested in plaintiff’s earlier specifications (not here involved). But the moment the vacuum becomes absolute, the vacuum space is a perfect dielectric, as we have all been taught— consequently, since defendant does not pretend to have an absolute vacuum, it must have a vapor tube.
As matter of definition, commercial usage, or of mere words, the contention may be right; we are not concerned to go further into it. Let it be admitted that per se defendant has a vapor tube; the question still remains whether its vapor has any such causal connection with what the audion amplifier does as Hewitt’s vapor possesses in respect of the means or method of the claims at bar. This plaintiff never obtained a patent covering every amplifier that employed a vapor tube; at the most, his patents can only cover every vapor tube used to amplify by substantially the same means, or in substantially the same method, as Hewitt’s amplifier. It is we think admitted, and, if not, it is proven, that when a vapor of anything like the order of pressure necessary for the operation of Hewitt’s device be introduced into defendant’s amplifier it will not and cannot work. Why this is so is the crux of so much of this litigation as rests on the earlier patents.
On such a point this court can pretend to do no more than to carefully weight all the evidence, and attempt to base decision on facts, and on facts as simple as the evidence permits. In this instance, however, we can find no satisfactory basis for judgment, except the electronic theory as expounded by defendant’s expert, and not, we think, successfully combatted even in detail by plaintiff. Indeed, except for its application to the present case, plaintiff’s expert is firm in the same faith ; both regard the theory as the majority of men look upon the theory of the rotation of the earth.
As applied to this litigation, we find the fact to be that it is an essential part of the operation of the devices suggested by the earlier pat*398ents of plaintiff that the evacuated chamber must contain a gas or vapor capable of ionization; unless there be ionization, the devices will not work. Whereas defendant’s audion amplifier does not depend for successful operation on ionization, and only succeeds when the vacuum is carried so far that ionization has no effect upon the operation of the grid and other parts contained in the tube. Consequently in respect of the earlier patents the decision below was right and is affirmed.
[3] As to the two later patents, the fundamental difference between the parties is as to what they are for. We agree with the defendant that the specifications suggest no utility or purpose in respect of either the means or method patent except that of rectifying, in a wide sense of that word — i. e., keeping straight; for even the modification suggested for direct ciirrent is evidently intended only to prevent a reversal in direction of flow. Nor does the expert evidence lead to any other conclusion.
Plaintiff’s view may be thus stated: Hewitt’s invention was the introduction into an otherwise old evacuated chamber of a separately charged piece of metal which he called a shield. Patents can neither be framed in such language nor supported by such generalizations. It is vital to inquire: ' For what purpose did plaintiff put his shield into the tube, and what did he say it was good for, and what was it good for, after it was in ?
He put it there, as he repeatedly pays, to increase the reluctance to starting, and his effort is to use such increase of what he calls reluctance to prevent the anode, or an anodé becoming a cathode; that is, Hewitt’s shield, as shown and described, is for the purpose of maintaining a flow of'current steady in direction. The specifications have nothing to do with amplifying, as is admitted; wherefore plaintiff’s argument must come to this: That that part of defendant’s device called the grid is, when amplifjdng, performing substantially the same function in the same way as does plaintiff’s shield when rectifying— not that Mir. Hewitt ever had any ideas on this point.
On the evidence we can only say we think this is not true. The whole object of the grid is to receive variations of potential which are by such reception, impressed upon the output current; but plaintiff’s shield cannot vary in any way the current flow between any two electrodes. Indeed, after prolonged study of this evidence, we fail to perceive any other resemblance between plaintiff’s shield and defendant’s grid, except that they are both pieces of metal and both inserted into evacuated chambers.
We have not overlooked the long series of experiments conducted before the lower court, but described with the aid of diagrams and photographs in this record. They may be summed up thus: Amplification for telephonic purposes may be accomplished with a mercury vapor (or other similar gas) apparatus, but none of the apparatus produced by plaintiff failed to depend for whatever measure of success it attained either upon ionization, or a radical departure from anything disclosed, or upon both.
Decree appealed from is affirmed, with costs..
The disclosures of this patent were considered in Marconi, etc., Co. v. De Forest, etc., Co. (D. C.) 236 Fed. 942.