(after stating the facts as above). [1] We accept-the statement of counsel that the objects aimed at by this patentee, and sought to be covered as to the means of attainment, by the claims in suit are three:. (1) The provision of a secure, but readily removable and replaceable, panel, giving easy access to the chute interior. (2) The provision, between said panel and the fixed portion of the chute, of a joint so positioned and formed as to prevent or lessen the catching of descending letters, etc., in such necessary joint or meeting of parts. (3) Furnishing an _efficient means of securing in closed or operative position the panel aforesaid. We are satisfied that he has attained them all, and defined the means of accomplishment by claims. This record presents the questions whether plaintiff’s means -required invention in the devising, and whether defendant, in attempting to reach the same goal (open to all), has been guilty of infringement.
The inventive worth of what is disclosed by the applicant ,for a patent largely depends on the extent to which the field in which he works has been fertilized by preceding laborers. The attainment of a desirable and even difficult result does not permit the court to forbear scrutiny of the means of attainment; for it is only with that department of intellectual effort that the patent law is concerned. Wood v. Kahn (C. C.) 189 Fed. 399, affirmed 198 Fed. 403, 117 C. C. A. 193. This is fundamental, even though it remains true that, if many have sought the result without success, or the thing produced supplies a real public demand therefor, the fact of success is some evidence of invention.
When a department of human enterprise has, for the term of years allowed by law, been exclusively occupied by one person, through ownership of pioneer and basic patents on which a large business has been erected, such lawful monopoly necessarily tends to divert independent inventors or improvers from a field in which their only present market is the patent owner, who -is doing very well without them, and as naturally produces improvements devised hy or on behalf of the owner of the business, built on the basic patents, that oftentimes rather satisfy a mercantile desire for the continuance of patent protected *511trade, than any scientific difficulty, or public demand. There is nothing unlawful about this, but when improvement patents in such long restricted, if not completely monopolized, branch of trade, are put to the test of forensic discussion, the absence of prior or even contemporary efforts in the same direction cannot, with any force, be used as evidence or argument to support them.
This plaintiff’s business is the most striking example of such lawful restriction of competition, as yet presented to us. Not only did the expired Cutler patents create in effect a monopoly of the mail chute concept, but, since there was small market for the product, unless the letter box at the chute bottom became part of the postal system of the country, former departmental regulations practically required conformity to the expired patents, and the present rules confine official recognition to chutes on which we think certain of the claims in suit must plainly read, until some bold inventor finds a closure for a box, which is not a door, lid, cover, or casing. It accordingly results that the art prior to the patents in suit consists substantially of the expired Cutler patents, supra, and the plaintiff’s practice under them.
We therefore briefly indicate what (material to this issue) plaintiff did under the expired patents, what the patents in suit disclose, and what defendant does or has done.
The 2,000 chutes put out by plaintiff as above stated, under (especially) No. 390,347, were formed of parts, assembled into a continuous vertical conduit, showing everywhere, except at mail entrances, the transverse horizontal section of Fig. 4 of that patent.
The metal chute body (iy) is seen formed into a rectangle, whereof one side is omitted, except the “flanges” (ii); to which flanges the glass frame (B) is affixed, by clamp strips (a, b) within and without the box of the chute, and riveted together (k). The clamp strips were made of elastic metal as long as the chute section, secured over the flanges by the rivets, and the glass panel then slid between them, the elastic clamps yielding to let it in1 and holding the panel in place by pressure.
A desideratum, in any device of this kind, was and is to make an interior surface so smooth that letters would not catch in chinks, cracks, or the like, and so clog the chute. Therefore the rivets were countersunk, and the “bar” interposed between superimposed chute sections was beveled so that its lower edge projected into the chute slightly, *512like the eave of a roof. This was to deflect falling fetters from the necessary crack, where one clamped panel ended and another began, as is set forth in the specification. In this construction, as may be plainly seen, the glass panel was not intended to be in the vertical plane of the chute flanges, the inner clamp (b) did not go into the corner, or cover the whole flange, and that clamp projected into the completed chute. As long as the rivets held, and no one disturbed the fitting of the superposed sections, there was no crack or crevice on the panel interior, except as shown above, and also where sections met, and 'that was protected by the bevel of the “bar” over one and under the next glass front.
Nevertheless clogs occurred, and to remove them it was necessary to remove the panel; that (says the patentee) was a simple matter, but the proper replacing “absorbed my attention,” because such removal disturbed the shop fit, and if at some part of its length (several feet) the inner clamp (b) sprang away from the glass, a crevice appeared, fatally attractive to falling letters.
The first patent in suit discloses a movable panel, in the form described a door, hinged at one side and provided with studs on the other, which studs engage appropriate parts of a locking device arranged on the proper side of the chute body. The structural differences (so far as material) between chutes under this patent and those of the expired patent may be seen in the subjoined detail in transverse section of a hinge corner; the opposite, or locking corner is the same, so far as here important. The diagram is part of Fig. 4 of No. 758,128.
It is here seen that the chute body is flanged as before (18), that the panel now has a frame (19) around which the elastic inner and outer clamps (88, 83, not necessarily integral) pass, holding the glass front (81) in place by pressure. This construction meets postal requirements (apparently passed to cover such construction), in that the key of the contrivance can be and is given the letter carrier, and, if a clog occurs, he opens the door of the choked section, pulls out the letters, and locks the door again. Tetters still catch; this device enables them to be reached by means of a key, instead of a mechanic.
The second Cutler patent discloses a system of affixing the several chute sections to the wall by means placed underneath or behind hinged crossbars, on the panel front of the structure, which, when locked in place, at once secure the panel doors in shut or operative position, and ■cover up the means by which the chute is fixed to the supporting wall. *513Defendant’s first form of chute, gives in transverse horizontal section the form below (one corner only shown).
The second form of alleged infringement produces a corner-said by plaintiff to be the following (on each corner):
Defendant’s chute section has a lid or cover, seen to fit over the projection or ridge A in the two last diagrams, and locking is effected by a cross bar binding the top of the lid (panel) when in closed position. To remove the panel and get at chute interior, the bar is unlocked and removed (it is not hinged), which enables one to lift the panel out of its engagement at the end remote from the locking bar. All defendant’s chutes are fastened to the wall by screw's, with heads defaced.
The detailed statement, now concluded, seems to us to fully show, the simple, if not elementary, nature of the mechanical or scientific disclosures on which the patents in suit base exactly 100 claims. That mail chutes grew in popularity while the basic patents were alive, that the Postmaster General was glad to have a locked c.bute, as well as a locked letter box at its bottom, and that these facts combined to make the more elaborate and expensive construction marketable, we do not doubt; the evidence is full to the point; but neither fact proves invention; and it may be added that the now patented devices do not prevent or lessen clogging of chutes. They only provide easier access to the choked region, and facilitate cleaning chute interiors.
*514This cause does not require us to consider whether there was invention in any detail of the disclosed construction. That particular form (for the claims in suit) is but one embodiment of the concept of the claims, nor does the defendant’s apparatus bear any resemblance worth mention to plaintiff’s specific disclosures.
Of the first patent, we hold the third claim invalid, because there was no invention in putting an “independently movable” panel, door, lid, or cover on the mail chute of the prior art. The language of Victor, etc., Co. v. Hawthorne, etc., Co., 178 Fed. 455, 101 C. C. A. 439, is thought applicable to this claim.
In so far as claims 5 and 7 of this patent advance as an element of invention a panel “having portions projecting inwardly beyond” the chute walls, they suggest nothing patentable. The claims on their face describe a door or lid that projects slightly into the receptacle it closes. The fact is old to common knowledge, and there is nothing in the specification to require separate consideration.
Claims 4, 6, and S present the gist of controversy. Taking No. 6 as typical, the question is whether there was invention in (a) removing the meeting edge of panel and chute from the chute corner, and (b) projecting a part of the panel (substantially as specified and for the purpose stated) inward and beyond the meeting place of door and chute.
[2] The positioning of the meeting edge is just where it was in the chute of the expired patent, and the inner clamp of -that patent projected into the chute; there was a vertical crack at the meeting of clamp and flange, and so is there in the construction of the claim. The only novelty shown or claimed is to treat the inner clamp strip as a part of the panel and give it the shape shown in diagram above (23). As pointed out, a general claim for any inward projection is invalid, and, when these more specific claims are examined, we find the old crack or meeting place still existent, and the means (i. e., projection) of minimizing its evils no more than an obvious adaptation of the bevel of the expired patent and common knowledge. That one bevel is vertical and the other horizontal is an immaterial difference. All the elements of these claims are old, and the function suggested for their combination is not reached by new method or means; nor do we think it is attained at all, as letters still stick for the same reasons as prevailed before this form of construction. We find these claims invalid for lack of patentable invention over the prior art. Where all the elements of invention are old but one, and the addition of that one is not invention, even a combination claim is void. Herzog v. Charles Keller Co., 234 Fed. 87, 148 C. C. A. 101.
We may add that, even assuming validity, the defendant’s second form plainly avoids infringement.
The fourteenth claim presents no question not covered by, the foregoing, while the nineteenth requires us to hold, as we do, that the addition of locking devices genetically to a mail chute is not invention; ■the point needs no more than mention. It is not pretended that there is any similarity between the locks of the parties.
The second patent required us only to point out, that defendant does *515not have any “means of securing the chute to the support” other than the screws of an art older than mail chutes: nor has it any means for at once preventing access to its screws and “securing” its “removable panel” (1. e., locking its lid), other than a bar lock, which likewise antedates the special art under consideration.
A mail chute is a long, narrow conduit, built of boxlike sections set on end. To fasten such boxes to a support, and put doors or lids on them, and then lock them, so. that no one can either open them or take them down without violence, is doubtless a good thing; hut a claim for the means or method of accomplishment must show invention in the mechanism. If in this claim the word “conduit” were substituted for “mail chute,” the nature of plaintiff’s demand would be plainer. There is no magic in “mail chute”; the mechanical question, and therefore that of invention, is just what it would be as to any other boxlike, sectional conduit for the transmission of solids by gravity, unless the inventive thought has mechanical relation to the peculiar thing transmitted. This claim has not, and the specification does not help it out; therefore if shows no invention.
The decree below is reversed, and the cause remanded, with directions to dismiss the bill for lack of invention in the claims sued on, with costs in both courts.
. In Fig. 4 only one clamping device is shown; that on one side being omitted to show plainly the flange construction.