Full opinion text
McNAMEE, District Judge. Thomas F. Peterson is the President and principal stockholder of Preformed Line Products Company (an Ohio corporation), plaintiff in this action. Peterson is an electrical engineer, and in 1936, while employed by The American Steel •& Wire Company, at Worcester, Massachusetts, he filed an application for Patent No. 2275019 (hereinafter Patent No. 1), which issued on March 3, 1942. At the time the patent issued, Peterson was Manager of the Electrical Products Division of The American Steel & Wire Company, at Cleveland, Ohio. In 1943 Peterson made arrangements with The Fanner Manufacturing Company (also an Ohio corporation) to manufacture the preformed helical elements which, in combination with an electrical cable, constitute the invention of Patent No. 1. In 1944 Peterson granted Fanner a non-exclusive license to make and sell the devices described in the patent. Subsequently additional licenses were granted by Peterson to The Cleveland Wire & Spring Company and The Ervine Manufacturing Company. However, for several years, Fanner continued to be the sole manufacturer of helical preformed armor rods under Patent No. 1 for Peterson’s employer, The American Steel & Wire Company. The No. 1 patent is the basic patent for helical preformed reinforcements used in ■combination with line conductors. Generally, the claims of Patent No. 1 define •a preformed open helix, having a pitch length several times its diameter and capable of substantial elastic deformation manually whereby it may be laid sidewise against the conductor and wrapped therearound without permanent deformation of the helix, the inside diameter of the helix being substantially equal to the outside diameter of the conductor. Although the specifications and claims of the patent are silent on the subject, the drawings show helical reinforcements with a hand of lay (direction of twist) of the helix in the same direction as the hand of lay of the strands of the conductor and also a lay in the opposite direction. The armor rods (reinforcements) manufactured by Fanner under the patent were made on specifications furnished by The American Steel & Wire Company under the supervision of Peterson. The armor rods were formed into helical configurations having an internal diameter slightly smaller than the external diameter of the cable. At the outset the armor rods manufactured by Fanner had a hand of lay opposite to that of the strands of the cable. Later, as the stranded conductor, known in the trade as A.C.S.R., came into more general use, the hand of lay of the helix was changed to conform to the direction of lay of the strands of the cable. On June 23, 1945 Peterson filed his patent application No. 601245, which matured into Patent No. 2587516 (hereinafter Patent No. 2) under date of February 26, 1952. Nine claims are recited in Patent No. 2, which defines an invention consisting generally of a combination of a stranded conductor and preformed helices with a pitch and direction of lay “substantially the same as” the pitch and direction of lay of the strands of the cable and having a diameter less than the outside diameter of the stranded cable. On September 1, 1947, effective January 1st of that year, Peterson granted Fanner a non-exclusive license under both Patent No. 1 and Application No. 601245. In August 1947 Preformed Line Products was incorporated and became licensed in September 1947 under Patent No. 1 and the pending application for Patent No. 2. Although Peterson was the moving spirit in the organization of Preformed Line Products, he continued his full time employment with The American Steel & Wire Company until 1950, and was a salaried consultant of that company thereafter until 1956. On April 27, 1948 Peterson filed an application which matured as Patent No. 2609653 (hereinafter Patent No. 3) on September 9, 1952. Patent No. 3 contains but two claims and differs from Patent No. 2 in that the helical convolutions therein described have a pitch length “slightly less” than the pitch length of the strands of the conductor. Meanwhile, on September 20,1946, Patent Application No. 698312 was filed by Peterson. That part of the application which related to dead ends was divided, and in December 1955 the dead end application was filed. Patent No. 2761273 (hereinafter Patent No. 4) issued on that application on September 4, 1956. In 1940 Jesse C. Little, an electrical engineer, became an employee of The American Steel & Wire Company, at Cleveland, Ohio. Little assisted in the establishment of the Vibration Fatigue Laboratory of the company and was active in making and supervising laboratory tests of the helical elements described in the above mentioned patents. Little left his employment with The American Steel & Wire Company in 1950 and became associated with Preformed Line Products as an employee and shareholder. In March 1954 Little sold his stock interest in and severed his employment with Preformed Line Products. In September 1954 he became an employee of defendant Fanner Manufacturing Company and is presently employed by that company. In 1948 Fanner ceased manufacturing and selling armor rods. Beginning in 1953 defendant resumed the manufacture and sale of such items and a few years later engaged in the manufacture and sale of dead ends. Defendant paid to plaintiff royalties in the approximate amount of $125,000 on all armor rods manufactured and sold by it. Defendant also tendered to plaintiff royalties on dead ends which it manufactured and sold. Plaintiff, however, refused to accept the latter royalties. THE PLEADINGS In its complaint plaintiff alleges that defendant infringed Patents Nos. 3 and 4 and that defendant engaged in unfair competition with plaintiff. The prayer is for injunctive relief, an accounting and damages. In its Amended Answer and Counterclaim defendant challenges the validity of Patents Nos. 3 and 4; denies infringement and avers that by its acceptance of royalties plaintiff is estopped to assert Patents No. 3 and No. 4 against defendant. As a further defense, defendant avers that it has the right under its license to make and sell any of the products disclosed in Patents Nos. 3 and 4. Defendant alleges that plaintiff has misused the patents in suit; has engaged in unfair competition with defendant and that plaintiff has violated the antitrust laws of the United States. Thus, the issues are: 1. The validity of Patents No. 3 and 4. 2. Infringement of said patents. 3. Whether defendant competed unfairly with plaintiff. 4. Estoppel and implied license. 5. Misuse of the patents. 6. Violation of the antitrust laws. IS PATENT NO. 3 VALID ? Defendant contends that the invention described in Patent No. 3 was in public use and on sale more than one year before the application for the patent was filed on April 27, 1948. In support of such contention defendant relies largely upon oral testimony and an exhibit which, together, show that on September 27, 1946 Edward Schane, Chief Engineer of Fanner, received specifications from The American Steel & Wire Company, or Peterson, setting forth the pitch lengths of the various types of helical reinforcements to be manufactured by Fanner, Thereafter Fanner manufactured armor rods in accordance with such specifications. The diameter dimensions of the cables were also set out in the specifications but no reference was made therein to the pitch length of the cables. Defendant contends, however, that the preferred pitch length of the cables under standards set up by the American Society for Testing Materials is 13 times the diameter and that the application of such formula discloses the pitch length of the cables to be greater than the prescribed pitch length of the reinforcements. It appears, however, that the A.S.T.M. standards were not adopted until 1948, which, of course, was later than the critical period of alleged prior use. Moreover, defendant’s witness, J. C. Little, testified that in 1945-1946: “We were not always or in fact never sure or certain of the lay lengths which were going to be on the strands on which they (the reinforcements) were to be applied.” The claims of the patent describe a combination of a cable and a helical reinforcing device. In order to establish prior public use of the invention it was necessary to show the use, prior to April 28, 1947, of a reinforcing.device in combination with a cable in which the former had a shorter pitch length than the latter. The defendant was unable to submit such proof. It is the teaching of the cases that prior public use must be established by evidence that is so clear, convincing and cogent as to admit of no reasonable doubt. Interurban Ry. & Terminal Co. v. Westinghouse Electrical & Mfg. Co., 186 F. 166, 169 (6th Cir.); Zachos v. Sherwin Williams Co., 177 F.2d 762, 763 (5 Cir.); Fraser, et al. v. Williams, D. C., 61 F.Supp. 763; Austin Machinery Co. v. Buckeye Traction Ditcher Co., 13 F.2d 697, 700 (6th Cir.). Defendant has not sustained the burden of proof on this issue. Defendant contends also that the No. 3 patent lacks adequate disclosure. This contention rests almost entirely upon the alleged indefiniteness of the term “slightly less” as used in the claims of the patent. There is a difference of opinion among the witnesses as to the meaning of “slightly less” but such divergence of views is hardly enough to warrant the invalidation of the patent on that ground alone. Compare: General Electric Supply Corp. v. Maytag Corp., 100 F.2d 218, 223 (8 Cir.). Considering the nature of the invention, it is difficult to perceive wherein the patentee could have used a more precise term to describe the pitch length of the reinforcement in relation to that of the strands of a conductor. In Eibel Process Co. v. Minnesota & Ontario Paper Co., 261 U.S. 45, at p. 66, 43 S.Ct. 322, at 329, 67 L.Ed. 523, it was contended that the word “substantial” was so indefinite as to render the patent void. In answering this argument, the court said: “ * * * Expressions quite as indefinite as ‘high’ and ‘substantial’ in describing an invention or discovery in patent specifications and claims have been recognized by this Court as sufficient. In Tilghman v. Proctor, 102 U.S. 707 [26 L.Ed. 279], the claim sustained was for ‘the manufacturing of fat acids and glycerine from fatty bodies by the action of water at a high temperature and pressure.’ See also Rubber Co. v. Goodyear, 9 Wall. 788, 794 [19 L.Ed. 566]; Mowry v. Whitney, 14 Wall. 620, 629 [20 L.Ed. 860]; Lawther v. Hamilton, 124 U.S. 1, 9 [8 S.Ct. 342, 31 L.Ed. 325] ; Carnegie Steel Co. v. Cambria Iron Co., 185 U.S. 403, 436 [22 S.Ct. 698, 46 L.Ed. 968]; Abercrombie & Fitch Co. v. Baldwin, 245 U.S. 198, 205 [38 S.Ct. 104, 62 L.Ed. 240].” It seems reasonable to conclude that persons skilled in the art would understand the meaning of “slightly less” when that term is read in the full context of the claims and considered in the light of the prior art. Defendant claims also that Patent No. 3 does not disclose invention. This defense rests upon two grounds — (1) that Patent No. 3 discloses no invention over the prior art; (2) that the claims of Patent No. 3 disclose no invention over and above the claims of Patent No. 2, which issued on a co-pending application of the patentee. (1) As anticipations, defendant relies upon Peterson’s Patent No. 1, Sherman No. 2172810, Sel-quist No. 2202538. The above prior patents were cited by the Patent Office during the prosecution of the application. It is well established that citations by the Patent Office of pertinent prior art adds weight to the statutory presumption of validity. Cold Metal Process Co. v. Republic Steel Co., 233 F.2d 828, 837 (6th Cir.); Southern States Equipment Corp. v. U. S. C. O. Power Equipment Co., 209 F.2d 111, 118 (5 Cir.). Defendant also cites and relies upon a publication authored by J. C. Little and Thomas F. Peterson entitled “Conductor Reinforcements,” which was read by Little at a conference of the Missouri Valley Electrical Association on April 17, 1947 and copies thereof distributed to the membership of the Association. Defendant cites the following portion of the publication as anticipating the shorter pitch length of Patent No. 3: “Basically P. F. T. armor rods consist of hard-spring-type wires preformed as helices with a pitch length which is eight to ten times that of the conductor or strand, etc. * *.” The publication indicates no preference between the same or opposite lay and makes no reference to the pitch length of the conductor strands. Defendant attempts to supply this latter deficiency by oral testimony relating to the general range of pitch lengths of cables at the time in question. It is well settled, however, that critical omissions in a prior publication cannot be supplied by oral proof. Dewey & Almy Chemical Co. v. Mimex Co., 124 F.2d 986 (2 Cir.). See also: Lincoln Stores v. Nashua Mfg. Co., 157 F.2d 154 (1 Cir.). (2) The application for Patent No. 2 filed on June 12, 1945 was co-pending with the application for Patent No. 3 from the filing date of the latter on April 27, 1948 until the patent issued on the former in February 1952. Because the application for Patent No. 2 was not disclosed to the public at the time the application for Patent No. 3' was filed, the former application cannot be considered as prior art. However, where two patents issue to the same inventor on his co-pending applications, the claims of the later patent cannot be sustained as valid unless they disclose invention over the claims as 'distinguished from the disclosures of the earlier grant. In re Sherman, 121 F.2d 527, 28 CCPA 1329; In re Land, 109 F.2d 246, 27 CCPA 863; Weatherhead Co. v. Drill Masters Supply Co., et al., 227 F.2d 98 (7 Cir.); S. H. Kress & Co. v. Aghnides, 246 F.2d 718, 726 (4 Cir.). Both Patents Nos. 2 and 3 provide for a direction of lay the same or substantially the same as the lay of the strands of the cable. In all but three of the nine claims of Patent No. 2 the pitch length of the helical reinforcements is described as being “substantially the same as” the pitch length of the strands. In Claim No. 3 of Patent No. 2 the pitch length of the reinforcement is described as “substantially corresponding to the pitch length of the strands of the cable.” Only in Claim No. 2 of Patent No. 2 is the pitch length of the helical reinforcements defined as “the same” as the pitch length of the strands. Claim No. 3 of Patent No. 2 and Claim No. 1 of Patent No. 3 appear in the margin. The primary purpose of Patent No. 2 was to secure substantial correspondence between the angle and length of the pitch of the helical elements with the angle and length of lay of the strands of the conductor so that the helical elements would lie between and “track” with the adjacent strands of the conductor. It was conceived that by such arrangement the greatest line contact between the helical elements and the conductor strands would be realized and result in the highest frictional engagement between the two and provide the greatest area of contact for electrical purposes, thereby effecting a union of highest efficiency in their relationships. In actual use, however, the invention of Patent No. 2 failed to produce the superior results claimed for it. This was recognized by the inventor in his preamble to the disclosures of Patent No. 3, where he said: “Notwithstanding the above desiderata, there is the fact that helices so preformed to this ideal pitch are subject to axial distortion when applied to stranded bodies working under tensional loads of relatively high values, as are encountered in overhead transmission, line assemblies and in other suspended strand constructions. The tendency is for the helical elements to be elongated so that their position between adjacent strands of the associated conductor is disarranged to the extent that they tend to pull out of the inter-strand groove and ride up over adjacent strands to positions which are less efficient in the matter of contact from both the electrical and mechanical viewpoints. As is well known, if a helix is stretched so as to increase its pitch length, its effective helical diameter is diminished. Therefore, in the elongated condition of load, mentioned above, the helical element exerts its greatest constrictive effort in the new disarranged position, and thus tends to build up high unit stresses at points where it rides over the strands of the associated conductor. Such stresses may be of a magnitude sufficient to notch or indent the strands, as well as the helical elements themselves, to afford places of low resistance to fatigue. Having started from an ideal condition, then, the arrangement of an accurately preformed helix tracking in the inter-stranded grooves of a conductor must change for the worse, if it changes at all, so as to result in an electrical and mechanical bond that is inferior to that originally constituted.” The patentee then specified the objective of Patent No. 3 as follows: “The present invention is aimed at curing these defects by providing for a helical element that is preformed with an angle of pitch that is less than the angle of lay of the associated stranded body, and with a pitch length that is less than the length of lay of the latter.” Thus, initially it was the objective of Patent No. 3 to cure the defects of the invention defined in Patent No. 2 by making the pitch lengths of the reinforcement “less” than the pitch lengths of the strands of the conductor. However, as allowed, the claims of Patent No. 3 define the pitch length of the reinforcement that is “slightly less” than the pitch length of the strands of the conductor. The issue to be determined therefore is whether the “slightly less” pitch lengths of the claims of Patent No. 3 are patenta-bly distinguishable over the pitch lengths of the reinforcements as defined in the claims of Patent No. 2. The claims of Patent No. 2 do not require exact or precise correspondence between the lengths of the pitches of the reinforcement and the strands. The phrases “substantially the same as” and “substantially corresponding to” imply clearly that something less than exact correspondence is required. The specifications of Patent No'. 2 confirm this view. “Although it is desirable that the pitch of the helix in which the reinforcing wires 20 are formed be the same as the pitch of the strands of the cable, the pitches may be at somewhat of a variance without materially impairing the effectiveness of the reinforcement.” Patent No. 2, col. 4, lines 58-63. Claim No. 3 of Patent No. 2 reads in part: “ * * * the pitch length of said elements when positioned on said cable substantially corresponding to the pitch lengths of the lay of the strands in the cable so as to tend to track with the latter * * *.” Patent No. 2, Claim 3, lines 54-57. Claim No. 3 of Patent No. 2 was first submitted as an amendment to the application on April 19, 1950. In urging the allowance of said claim before the Examiner, the patentee said: “This is one of the more limited statements, reciting, as it does, the condition of conformance of pitch and lay on the one hand, and introducing on the other, the condition of near conformance explained in the specifications at p. 8 commencing with line 16 and running through line 26. In short, this claim covers the practical form, as distinguished from the theoretical ideal, and should be patentable for the many reasons mentioned herein and previously on this record.” Ex. 36, p. 41. The condition of “near conformance” and tendency to track as taught in Claim 3 of Patent No. 2 is achieved also by the “slightly less” pitch length of the reinforcement as provided in Patent No. 3. It is stated in the specifications of Patent No. 3 that: “By this construction * * * any change must, from this initial condition be for the better by virtue of the fact that the helical element comes more closely into a condition of tracking * * Patent No. 3, col. 4, lines 33-39. During the prosecution of Patent No. 3 patentee’s counsel stated to the Examiner that: “ * * * it was here proposed to provide the helically-preformed reinforcement with a sufficiently short pitch angle and pitch length in relation to the strands of the conductor to be capable of being stretched into inter-strand agreement with the latter if and when such reinforcement were deformed by the application of tensile pull under conditions of actual use.” Ex. 1, p. 36. At the time the last quoted representation was made the patentee was prosecuting an applicationjíor the allowance of claims defining pitch lengths of the reinforcements as “less” than the pitch of the strands of the conductor. There was nothing new in making pitch lengths of the helical elements shorter than the pitch length of the cable. As shown by the file wrapper of Patent No. 3, the Examiner repeatedly refused to allow claims limited only to a pitch length that was “less” than the pitch of the cable and cited Peterson No. 1, Selquist, Sherman and other patents as prior art and disclosing such shorter pitch lengths. It was only after a conference with the Examiner and the cancellation of all ten claims of the original application and the substitution therefor of claims for pitch lengths “slightly less” than the pitch lengths of the conductors that the application was approved. While the specifications of Patent No. 3 use the term “less” in referring to the relative pitch lengths of the reinforcement and the cable, such use cannot enlarge the meaning of “slightly less” as used in the claims. Specifications may be looked to for the purpose of explaining any ambiguity in the claims or limiting their scope but specifications are not available to expand the claims. Walker on Patents, Deller Ed., Vol. 3, p. 1242, and cases cited therein. And, as said in Schriber-Schroth Co. v. Cleveland Trust Co. et al., 311 U.S. 211, 220, 61 S.Ct. 235, 239, 85 L.Ed. 132: “It is a rule of patent construction consistently observed that a claim in a patent as allowed must be read and interpreted with reference to claims that have been cancelled or rejected, and the claims allowed cannot by construction be read to cover what was thus eliminated from the patent.” See also Morgan Envelope Co. v. Albany Paper Co., 152 U.S. 425, 14 S.Ct. 627, 38 L.Ed. 500. The term “slightly less” connotes a small or trivial shortening of the pitch length and does not exclude the least reduction in the length of the pitch of the reinforcement below that of the pitch of the conductor. The term “slightly less” includes those minimal deviations from precise conformance in the pitch lengths of the reinforcements and the strands as taught in Patent No. 2. The claims of each patent, therefore, read on the other, thus meeting one of the tests of double patenting. In re Stanley, 214 F.2d 151, 41 CCPA 956. Moreover, no good reason appears why, if allowable, the claims in Patent No. 3 could not have been included in Patent No. 2. See Sterling Varnish Co. v. Louis Allis Co., D.C., 145 F.Supp. 810, 816. Patent No. 3 involved no new principle and represents no creative thought. It was the mere carrying forward of the original idea of Patent No. 2 to secure the ideal condition of “tracking” under conditions of actual use. As shown above, this same objective was sought to be accomplished by the practical form of “near conformance” as disclosed by Claim No. 3 of Patent No. 2. The conclusion is inescapable that the “near conformance” of pitch lengths as taught in Patent No. 2 contemplates a pitch length of the reinforcement “slightly less” than the pitch of the strands of the conductor. Quite apart from the foregoing considerations, the claims of Patent No. 3 do not disclose invention over those of Patent No. 2. A slight reduction in the pitch length of the reinforcement represents no more than the application of mechanical skill in the course of natural development of the art. Concrete Appliance Co. v. Gomery, et al., 269 U.S. 177, 46 S.Ct. 42, 70 L.Ed. 222; Saranac Automatic Machine Corp. v. Wirebounds Patents Co., 282 U.S. 704, 713, 51 S.Ct. 232, 75 L.Ed. 634. The defective performance of the invention of Patent No. 2 under high tension loads was caused by the elongation of the pitch lengths of the reinforcements beyond the length of the strands of the conductor. To anyone skilled in the art, it would be obvious that a slight reduction in the pitch length of the helices would eliminate the defects. It is too firmly established to require citation of authority — that a mere change in degree, form or size — does not constitute invention nor do improvements that are the result of mechanical skill amount to invention. It does not appear that the invention described in the claims of Patent No. 3 is substantially different from that comprehended in Patent No. 2. The following statement of the court in Miller v. Eagle Mfg. Co., 151 U.S. 186, 198, 14 S.Ct. 310, 315, 38 L.Ed. 121, is in point: “ * * * 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. * * * ” There is no need here to rely on the brighter light of retrospection to reach the conclusion that Patent No. 3 does not constitute invention. As was said in Hobart Mfg. Co. v. Landers, Frary & Clark, D.C., 26 F.Supp. 198; Aff’d. per curiam 107 F.2d 106 (2 Cir.): “ * * * it is obvious that a mere difference or change in the mechanical construction in size or form of the thing used, in order to obviate known defects existing in the previous devices, although those changes are highly advantageous, and far better and more efficacious and convenient, does not make the improved device patentable. In order to be patentable, it must embody some new idea or principle not before known. It must be a- discovery, as distinguished from mere mechanical skill or knowledge.” To the same effect is: Detroit Gasket & Mfg. Co. v. Victor Mfg. & Gasket Co., 114 F.2d 868 (7 Cir.); Pearson Sanding Machine Co. v. Williams Furniture Co., 132 F.2d 55 (4 Cir.). Plaintiff cites and relies upon Eibel Process Co. v. Minnesota & Ontario Paper Co., 261 U.S. 45, 43 S.Ct. 322, 67 L. Ed. 523, as authority for the proposition that a change in the degree of pitch may be patentable if directed to a wholly different object than the prior art. That Eibel is an inapposite citation is readily apparent upon an examination of the opinion in that ease. The pitch of the prior art in Eibel was described by the court as “trivial,” the sole object of which was to secure the drainage of the stock. This was accomplished by a pitch of 2 or 3 inches. Eibel’s pitch was directed to the entirely different object of increasing the speed of the stock to keep pace with the speed of the wire. To accomplish this Eibel raised his pitch to 12 inches and above and the higher pitch for this different purpose was at a different point in the paper-making machine than the lower pitch of the prior art. It is true that Patent No. 2 and its objectives were referred to in the application for Patent No. 3 and that the Patent Office was informed of the disclosures of the former. It is likewise true that the Patent Office consistently requires inventive differences between the claims of co-pending applications. In the light of these facts, it may well be that Patent No. 3 is entitled to a presumption of validity over Patent No. 2. However, such presumption is not conclusively binding on this Court, and, for the reasons stated above, I am of the opinion, and hold, that the presumption has been overcome and that the claims of Patent No. 3 do not disclose invention over and above Claim No. 3 and other claims of Patent No. 2 and that Patent No. 3 is invalid. INFRINGEMENT OF PATENT NO. 3 If, contrary to the above holding, Patent No. 3 is held ultimately to be valid, I am persuaded that in such event it would not be found that defendant infringed the patent. As shown above, claims defining the pitch length of the reinforcement as “less” than that of the strands of the cable were rejected by the Patent Office, after which the patentee cancelled such claims and substituted the allowed claims, defining the pitch length of the reinforcement as “slightly less” than the pitch length of the strands of the cable. Notwithstanding the Supreme Court’s pronouncement in Sehriber-Schroth Co. v. Cleveland Trust Co., supra, that — “claims allowed cannot by construction be read to cover what was thus eliminated from the patent” — plaintiff contends, in effect, that the term “less,” which was eliminated from the claims, may, by construction be included therein. Plaintiff advances the argument that the claims of Patent No. 3 provide for a range of pitch lengths between upper and lower limits. According to plaintiff, the lower limit is defined in the last four lines of Claim No. 1, which read: “of sufficiently open pitch for introduction to the line from its side without exceeding the elastic limit of the material of which it is made.” Plaintiff finds the upper limit of the supposed range of pitch lengths in the language of Claim No. 1, where the pitch length of the element is defined as “slightly less than the pitch length of the strands comprising said line when said element is initially positioned thereon.” (Lines 37-40 Claim No. 1.) Mr. Sessions, the only disinterested witness who testified on the subject, took the view that the claims did not provide for such a range of pitch lengths but that the limitation inserted by the patentee in the claims to secure their allowance specifically requires the pitch length of the helical element to be “slightly less” than that of the strands of the conductor. Unquestionably Sessions’ view is correct. Under the construction for which plaintiff contends, the pitch length of the helical element may be “less” or even “substantially less” than the strands of the line “when initially positioned thereon.” Such construction enlarges the scope of the claims by the incorporation therein of the very term which was eliminated therefrom and renders meaningless the language included in the claims to secure the allowance of the patent. Obviously the terms “less” and “slightly less” do not define the same length of the pitch of the element in relation to the pitch of the strands of the conductor. Plaintiff’s argument that the last four lines of Claim No. 1 define the lower limit of a range of pitch lengths is not persuasive. There is no showing that a helical element with a pitch length “slightly less” than that of the strands of the conductor when initially positioned thereon cannot be applied thereto without exceeding its elastic limits. Indeed it would appear that a longer pitch length only “slightly less” than that of the strands would more readily meet the requirements of the last four lines of the claim than a shorter pitch length which is “less” or “substantially less” than that of the strands of the cable. Plaintiff’s argument is no more than a vain attempt to avoid the express limitation which the patentee inserted in the claims to secure their allowance. Apparently doubting the soundness of the above argument, plaintiff advances the alternative contention that the term “slightly less” includes pitch lengths 50%-shorter than the pitch lengths of the strands. Ruhlman, Vice President of plaintiff, testified, in effect, that “slightly less” includes pitch lengths 50 % shorter than the strands of the cable. Both the argument and the testimony on which it rests must be rejected. That 50% less is substantially rather than slightly less is too obvious to require further comment. Nor is plaintiff entitled to rely on the doctrine of equivalents. In addition to the rule laid down in Schriber-Schroth Co. v. Cleveland Trust Co., supra, plaintiff is bound by the somewhat broader principle consistently applied by the Sixth Circuit Court of Appeals. The principle, as stated in Lunati v. Barrett, 104 F.2d 313, 316 (6 Cir.), is: “The claims in suit must be narrowly construed within the principle so often applied in this court that where claims define an element in terms of form, location, or function, thereby creating an express limitation, where that limitation pertains to the inventive step and imports a substantial function which the pat-entee considered of importance, the court cannot be permitted to say that other forms which the inventor thus declared not equivalent are so to be treated. D’Arcy Spring Co. v. Marshall Ventilated Mattress Co., 6 Cir., 259 F. 236, 240; Hollingshead Company v. Bassick Mfg. Co., 6 Cir., 73 F.2d 543, 548; Directoplate Corp. v. Donaldson Lithographing Co., 6 Cir., 51 F.2d 199, and our recent decision in Valjean v. Perfection Stove Co., 6 Cir., 103 F.2d 60. Whether our conclusion be based upon estoppel in patent office proceedings or upon a limitation voluntarily inserted in the claims to avoid prior art seems to us unimportant. The result in claim construction is the same.” See also: Midland Steel Products Co. v. Clark Equipment Co., 174 F.2d 541 (6 Cir.); Dow Chemical Co. v. Skinner, 197 F.2d 807 (6 Cir.); Parke-Davis & Co. v. American Cyanamid Co., 207 F.2d 571 (6 Cir.). All cable reinforcements manufactured and sold by defendant have pitch lengths that are “less than” the pitch lengths of the cables. Most of such reinforcements have pitch lengths considerably shorter than “slightly less” than the pitch lengths of the cables of association and do not infringe the patent. According to plaintiff, defendant’s products show pitch lengths ranging from 61% to 96.2% of the pitch of the cables. The latter figure indicates the difference between the minimum standard pitch length of a %eth inch galvanized steel wire cable of 3.12 inches and the pitch of a helical reinforcement of 3 inches available for use in combination with such cable. The pitch lengths of such cables, however, range between the minimum of 3.12 inches and a maximum of 4.99 inches. The evidence does not show clearly whether defendant’s reinforcement with a 3 inch pitch was used in combination with cables of the above minimum or maximum pitch lengths or with cables of pitch lengths somewhere between the upper and lower limits of the cable pitches mentioned above. Similar situations exist with respect to other cables. Patent No. 3 defines a combination of cable and reinforcement. Defendant makes and sells only the reinforcement. In the state of the record it is impossible to determine whether defendant’s products with pitch lengths “slightly less” than those of the cables were used in the patented combination. It may well be that defendant sold reinforcements knowing the same could be used for infringing as well as non-infringing purposes. However, even if such were the fact and even if the patent were held to be valid, defendant could not be found liable as an infringer. As will hereinafter be shown, defendant had an implied license to make, use and sell the reinforcements defined by Patent No. 3 and plaintiff is estopped from asserting the patent against defendant. THE VALIDITY OF PATENT NO. 4 The invention described in Patent No. 4 is a division of the subject matter disclosed in parent application No. 698312 filed September 20, 1946. The patent issued on application No. 550580 filed December 2,1955, the date of issuance being September 4, 1956. The subject matter of the patent is “dead end for cables.” A dead end of the type described in the patent may be defined briefly as the addition or attachment to a wire or cable of a device or structure which provides a link between the wire or cable and the point of attachment in which the link carries the full load being terminated. Such dead ends are to be distinguished from those in which the wire or cable is bent back upon itself to form a loop and the bent end is secured to the main body of the wire or cable by means of clamping, eye splicing, etc. In the latter type of dead end the bent or looped portion of the cable or wire provides the means of carrying the load being terminated. The patent contains twenty claims. Article claims 1, 3, 5 and 8 through 14 and method claims 6 and 15 are alleged to be infringed. Defendant contends that the claims alleged to be infringed are invalid, as being anticipated by the prior art and for lack of invention. The references cited by the Patent Office are Moxham Patent No. 337513 (1886), Peterson No. 2275019 (Patent No. 1). Defendant advances the contention that certain drawings and specifications were added to the application in 1956; that because of the intervening five years of public use, the added materials should be disregarded. Implicit in defendant’s argument is the claim that inasmuch as these added drawings and specifications did not appear in the parent application, No. 698312, plaintiff is not entitled to the earlier application date. Defendant has not shown that the above amendments constitute new matter. The presumption is the other way. In General Electric Co. v. Cooper Hewitt Electric Co., 249 F. 61 (6th Cir.), the court said: “The rule is that insertions by way of amendment in the description or drawing, or both, do not hurt the patent, if the insertions are only in amplification and explanation of what was already reasonably indicated to be within the invention for which protection was sought * * The amendments here in question meet the requirements of the above rule. See also: Helms Products v. Lake Shore Mfg. Co., 222 F.2d 677 (7 Cir.) ; Wagenhorst v. Hydraulic Steel Co., 27 F.2d 27 (6th Cir.) Defendant asserts that the half lays of preformed helical elements referred to in the claims and demonstrated in the drawings are to be found in Peterson’s No. 1 patent. In support of its claim in this regard, defendant relies upon the testimony of the patentee and statements made by the latter’s attorney to the Patent Office in the prosecution of the application for Patent No. 4. There is no express reference in the description of Patent No. 1 to half lays. However, the patent does show a plastic helical preformed half lay in one of the drawings. In his testimony relating to Patent No. 1, Peterson admitted that the drawing of the plastic half lay in Fig. 2 of Patent No. 1 was the equivalent of the “hand drawn wire preformed helical elements subassembled into a half lay.” During the prosecution of Patent No. 4, the Examiner rejected claims 8 through 12 as not being supported by the disclosure on the ground that “the 180 degree phase relationship of a helically preformed element is not disclosed as indicated above.” In reply, the applicant’s attorney said, inter alia: “In applicant’s original patent No. 2,275,019, helical strips are provided which are in 180° phase relationship as preformed, and which are the equivalent of the half-lays 5, 5a and 5b of the present ease.” (Pl. Ex. 5, p. 26.) Plaintiff argues that Peterson’s quoted testimony must be considered as referable only to the subject matter of Patent No. 1 and that the statements to the Examiner relate solely to the equivalency of the 180 degree relationship of the legs of the dead end. Such arguments fail to give effect to the inventor's unqualified admissions of the equivalency of the plastic strip and the half lay of Patent No. 4. Notwithstanding such admissions, it is clear that there is nothing in the disclosures of Patent No. 1 suggesting the use of half lays of helical elements as components of a dead end. The dead end of Patent No. 4 is a new and useful device serving a function capable of producing novel and beneficial results beyond anything suggested or contemplated by the disclosures of Patent No. 1. The terms “half lay” and “whole lay” appear in patent literature for the first time in the parent application for Patent No. 4. Even if it be assumed that “half lays” were old in the art at the time such application was filed, it is nonetheless clear that the dead end of Patent No. 4 constitutes a distinct advance in the art and represents invention over the disclosures of Patent No. 1. Such apparently was the opinion of the Patent Office which considered Patent No. 1. Nothing has been shown that successfully impeaches that opinion. Defendant relies heavily upon Selquist No. 2202538 as a pertinent prior art reference not cited by the Patent Office. Plaintiff contends that, although not cited by the Examiner, Selquist was considered by the Patent Office during the prosecution of the application for Patent No. 4. In support of such contention, plaintiff points out that Selquist was cited and an interference litigated with the application for Patent No. 1; that Selquist was cited as a reference in Patents No. 2 and 3; in the specifications of Patent No. 2 reference is m,ade to Patent No. 1; and in the parent application No. 698312 reference is made to Patent No. 2. These facts, however, do not demonstrate that •Selquist was considered as a reference against Patent No. 4. Nor does the fact that in 1951 the patentability of three dead end claims of Patent No. 2 was ap- . proved by the Examiner of parent application No. 698312 as well as the Examiner of the application for Patent No. 2, establish that Selquist was considered as a reference in approving the claims of Patent No. 4. The evidence discloses that in July 1951, during the prosecution of Patent No. 2, the applicant’s attorney clearly distinguished the dead end claims of that patent and the disclosures of the application for Patent No. 4. As a result of counsel’s argument in this regard, the Patent Office retained the three claims in question in Patent No. 2 instead of transferring them to the application for Patent No. 4. It does not follow that because Selquist was considered by the Examiner of application No. 698312 in examining three claims of Patent No. 2 in 1951, that he or another examiner in the same division considered Selquist in passing upon the claims of Patent No. 4 either before or after the divided application was filed in December 1955. Plaintiff contends further that it is as reasonable to conclude that Selquist’s patent was considered and cast aside as not pertinent as to conclude that it was inadvertently overlooked. Artmoore Co. v. Dayless Mfg. Co., 208 F.2d 1, 4 (7 Cir.). The reasoning of Artmoore and the cases cited therein is applicable in cases where it appears that the prior art not cited by the Patent Office was not pertinent. However, such is not the situation here. Indeed Selquist would seem to be a more pertinent reference than Patent No. 1. In many respects the three claims of Selquist are similar to claims 6, 7 and 8 of Patent No. 1. Each of the above claims of both patents provides for a portion of relatively straight wire integrated with the helical elements of the reinforcement. Neither the above claims of Patent No. 1 nor the claims of Sel-quist make any reference to a dead end. Fig. 10 of Selquist, however, illustrates a dead end in which the bight is formed by bending a portion of straight wire integral with the preformed helical elements of the reinforcement of the cable which is somewhat similar to the dead end of Patent No. 4. It seems highly improbable, therefore, that Selquist would have been cast aside by the Patent Office as not being a pertinent prior reference. Defendant contends that the presumption of validity of a patent “cannot exist over pertinent prior art not considered by the Patent Office” and cites and relies upon the following cases of the Sixth Circuit Court of Appeals: Deering Milli-ken Research Corp. v. Electrical Furnace Corp., 261 F.2d 619; O’Leary v. Liggett Drug Co., 150 F.2d 656; Royal Patent Corp. v. Monarch Tool & Mfg. Co., 203 F.2d 299. In each of the cited cases it was held that the prior art not cited by the Patent Office constituted anticipations of the patents in suit. As anticipations, such prior art was sufficient to overthrow the presumption of validity of the patents in controversy. However, where the patent in suit is not anticipated by pertinent prior art not cited by the Patent Office and lack of invention is not shown, the presumption of validity remains unimpaired. The expressions of the court in the cited cases upon which defendant relies must be read in the light of the court’s determination in each case that the pertinent prior art references not cited by the Patent Office anticipated the patent in suit. When so read, it becomes clear that in the cited cases the court did not hold nor do the opinions of the court imply that the mere failure of the Patent Office to consider pertinent prior art vitiates the presumption of validity of the patents in suit. The statutory presumption of validity rests on the premise that the Patent Office has fully performed its public duty of ascertaining whether the device or process for which a patent is sought constitutes invention. This entails, among other things, a determination whether the disclosures in the application are patentably distinguishable from all pertinent prior art patents. The presumption of validity is, of course, rebuttable and may be overcome by evidence showing inter alia that the Patent Office was in error in distinguishing the patent in suit from pertinent prior art considered by it or that pertinent prior art not considered by the Patent Office embodies patentable features of the issued patent and anticipates the latter or discloses lack of invention. But in the absence of proof showing an error in judgment of the Patent Office in either of the above respects no pertinent prior art reference is effective to overthrow the presumption of validity. Where, as here, a defendant relies on a pertinent prior art patent not considered by the Patent Office, he assumes the burden of showing that the reference upon which he relies anticipates the patent in suit. In my opinion defendant has not sustained that burden. The element of half-lays appears in Claims 1, 3, 5 and 6 of Patent No. 4. A half-lay may be roughly defined as a plurality of helical elements applied against each other and inter-twisted together. A half-lay is one-half of a tubular body of inter-twisted elements which constitutes a whole lay. Method Claim No. 6 of Patent No. 4 succinctly describes a dead end in which the bight consists of half-lays and the reinforcement of the cable is a whole-lay. Claim No. 6 reads: “The method of forming an elongated body having a bight integrally fashioned thereon, which comprises forming a half-lay of helically preformed elements, bending the half-lay back upon itself to define a bight and two half-lay legs, and intertwist-ing said legs to provide a whole-lay body upon said bight.” Claim No. 8 of the patent defines a dead end comprising an elongated body to be dead ended and a single helical element of constant open pitch throughout its length being bent adjacent its middle to form a bight with legs projecting therefrom, the legs being wrapped around said body so that the helix of one leg is in substantially 180 degree phase relationship with the helix of the other throughout their co-extensiveness along the elongated body. Claims 9, 10 and 11 are dependent upon Claim No. 8 and are substantially similar to the latter except that they provide for two or more helical elements. Claim No. 14 recites a plurality of helical elements “intertwisted into association coaxially with each other and, as associated, defining a relatively straight linear body gripping portion and a curved bight portion at one end of said gripping poi'tion.” The foregoing is sufficient to indicate the scope and nature of the teachings of Patent No. 4. The defendant relies solely upon the dead end illustrated by Fig. 10 of Sel-quist in support of its claim that the patent in suit is anticipated by Selquist. Fig. 10 of Selquist is similar to the dead ends of Patent No. 4 in the respect only that the reinforcement of Selquist which grips the cable is a helical element. The bight portion, however, consists of straight wire. Fig. 10 of Selquist is a dead end made of a reinforcement as shown in Fig. 4 of that patent which discloses a helical element at either end of the reinforcement with straight wire intermediate the respective helices. As indicated above, the straight wire is bent to form the bight. Thus the dead end of Fig. 10 of Selquist does not show a helical element of constant open pitch throughout its length bent adjacent its middle. There is no helical formation in the bight of the Selquist dead end. The plurality of helical elements in the bight of Patent No. 4 provide resiliency under load stress similar to that of steel springs. Such resilience is absent in the straight wire bight of Selquist. The use of a plurality of helical elements of the dead end in the patent in suit permits higher load-carrying capacities. These advantages are not found in the Selquist dead end. The dead ends of Patent No. 4 develop the full tensile strength of the cables to which they are attached, thus eliminating the need for using clamps. In the Selquist dead end, however, the full tensile strength of the cable is not developed and, as plaintiff argues reasonably, this may account for the suggestion in Selquist that clamps may be used. Mr. Sessions, the expert who testified on behalf of defendant, stated that under certain conditions it was difficult to maintain the elements in 180 degree relationship as shown in Fig. 10 of Selquist. In contrast, it appears that in Claims 8 through 12 and 13 of Patent No. 4 the legs of the helical elements are in 180 degree relationship or balanced in peripheral distribution. Such relationship aids in sustaining and supporting the cable and preventing its deflection. The annealed metal bight of Selquist, which is somewhat flabby, would not hold the legs of the helical element in the relationship taught by Patent No. 4. As indicated, the metal bight of Selquist comprises but a single straight wire bent in the middle. The Selquist patent contains no suggestion of multiple wires, but even if it did, a plurality of loops formed of straight wire would not provide the same cushioning effect or the resiliency found in the bight of the dead ends of the No. 4 patent. If multiple straight wires were formed into a bight, there would be an uneven distribution of stress, causing individual wires, bearing loads beyond their capacity, to break separately and, as one witness said, they would “go down like a string of dominoes.” In the bight of the helical elements of Patent No. 4 the load is evenly distributed among all elements. Thus, in the dead ends of Patent No. 4 the load-bearing capacity is much greater than in Fig. 10 of Selquist, and this would be true even if the single element of the latter were multiplied. Defendant argues that Claims 10 and 13 of the Selquist application, which were cancelled, provided for or suggested the use of helical elements in the bight and that such cancelled claims are anticipations of Patent No. 4. This argument is without merit. Cancelled matter in an application does not appear in the patent nor is it otherwise published. As plaintiff says: In Fessenden v. Wilson, 48 F.2d 422, 18 CCPA 1171, the Court of Customs and Patent Appeals said: “Such cancelled matter secreted in the files of the Patent Office is no more communicated to any one than if it were merely written out by the inventor and retained in his portfolio.” “For obvious reasons, the filing of an application, the description of which is cancelled before it results in a patent or comes to the public notice, is not such a published description of the invention as is within the inhibition of the statute. Milburn Co. v. Davis-Bournonville, supra [270 U.S. 390, 46 S.Ct. 324, 70 L.Ed. 651].” The practice of the Patent Office is to regard cancelled matter in the application file of the patent as no bar to the allowance of a patent. In the Manual of Patent Examining Procedure, 2d Ed., Nov. 1953, U. S. Patent Office, Department of Commerce, the following rule is stated: “Cancelled matter in the application file of a United States Patent is not a proper reference, since it is neither a patent nor a printed publication. See Fessenden v. Wilson, et al., 1931 C.D. 419; 410 O.G. 815.” The teaching of a prior art patent cannot, by reference, be enlarged to include disclosures which the inventor cancelled during the prosecution of his application in the Patent Office. Can-celled Claims 10-13 of Selquist therefore do not anticipate Patent No. 4. It would serve no purpose to examine in detail the many other arguments advanced by defendant in an effort to demonstrate the invalidity of Patent No. 4. All such arguments have been considered but enough has been shown above to indicate the Court’s view that Patent No. 4 discloses invention over the pertinent prior art. This is true with respect to the article claims in suit and also to method claims 6 and 15. The latter claims are distinguishable from the method taught by Selquist, which is to apply one end of the helical element to the reinforcement before the bight is formed. The method claims of Patent No. 4 teach the bending of the “half-lay” or “mutually conforming elements” before application to the conductor. The invention of Patent No. 4 with its plurality of mutually conforming helical elements — its half-lays and whole lays — the element of constant open pitch —the intertwisting of the helices and their coaxial relationship — the bending of multiple helical elements and the 180 degree relationship of the legs of one helix with the legs of the other — combine to produce a dead end that is a distinctly useful innovation. The invention has received defendant’s tribute of imitation. To a large extent, it has replaced the older and less efficient dead ends long in use in the electrical industry. The invention has achieved remarkable commercial success which, if the question of validity be considered doubtful, is sufficient to “tip the scales” in favor of the validity of the patent. Goodyear Tire & Rubber Co. v. Ray-O-Vac, 321 U.S. 275, 279, 64 S.Ct. 593, 88 L.Ed. 721. I hold Patent No. 4 to be valid. INFRINGEMENT OF PATENT NO. 4 No debatable question arises in connection with the issue of infringement of Patent No. 4. The defendant manufactures and sells dead ends identical with the dead ends of Patent No. 4. It is beyond dispute that defendant sold its dead ends knowing the same were specially made and adapted for use in the infringement of Patent No. 4. The evidence discloses a clear case of contributory and direct infringement of the article and method claims in suit. LICENSE AGREEMENT The License Agreement does not expressly include the subject matter of Patent No. 3. The only issue that merits discussion on this branch of the case is whether plaintiff is estopped to assert Patent No. 3 against the defendant by reason of an implied license to the latter under said patent. In September 1947, effective January 1,1947, Peterson granted a license to defendant under Patent No. 1 and application No. 601245 (Patent No. 2) to make, use and sell “cable reinforcements which constitute the subject matter of said letters patent and application aforesaid.” The royalty rate provided in the license is 10% of defendant’s net receipts until said royalties amount to $10,000, after which the royalty rate is 5%. Application No. 601245 was considered as an improvement of Patent No. 1 and described by the inventor as establishing an “ideal” relationship between the reinforcement and the cable of association. Yet within 7 months after the execution of the license agreement, Peterson filed an application for Patent No. 3, asserting in the preamble thereof that the aim of such application was to cure the defects which were found to exist under conditions of actual use in the invention described in the application for Patent No. 2. As indicated above, Patent No. 2 issued containing claims that provide for “near conformance” of the pitch lengths of the helical element and the conductor and which, in my opinion, are indistinguishable patentably from the “slightly less” pitch lengths of Patent No. 3. It is also my opinion that if any difference exists between the respective pitch lengths of Patents Nos. 2 and 3, such difference is merely one of degree and the result of mechanical skill. However, for the purpose of the discussion that follows, and for such purpose only, it will be assumed that Patent No. 3 is valid. After Patent No. 3 issued in September 1952, defendant resumed the manufacture and sale of helical reinforcements. All such reinforcements were of the same hand of lay as that of the conductors on which they were to be applied and the pitch lengths of the reinforcements were shorter than those of the strands of the cables. Defendant paid royalties to plaintiff on such reinforcements. Plaintiff accepted all such royalties over a period of 5 years to the time of the trial of this action in the amount of about $125,-000. Plaintiff says that it continued to accept royalties during the pendency of this action because defendant’s reinforcements were used in combination with a conductor in the manner claimed in the licensed patents, particularly Patent No. 1. Plaintiff explains its failure to notify defendant that the royalties were applicable only to Patents Nos. 1 and 2 on the ground that plaintiff was not informed that defendant’s products were made with the so-called short pitch. However, the true explanation of plaintiff’s conduct is found in considerations other than those urged by plaintiff. Patent No. 1 does not provide that the hand of lay of the helical elements shall be the same as that of the strands of the conductor nor does Patent No. 1 define the length of the pitch of the element in relation to the length of the pitch of the strands of the conductor as is the case in both Patents Nos. 2 and 3. Plaintiff knew that as far back as 1946-1947 defendant was manufacturing helical reinforcements for The American Steel & Wire Company of the same hand of lay as the conductor and making the pitch lengths of such elements shorter than those of the strands of the cable. Prior to August 1947, plaintiff had manufactured and sold a large order of short pitch reinforcements which were used successfully on the Bonneville Dam Project, a fact that was made known to the industry by an article in the Electric Light and Power magazine in March, 1948. The industry was informed by Patent No. 3 that the invention of Patent No. 2 performed defectively in actual use. Plaintiff was fully aware that Patent No. 2 was a commercial failure and had been superseded by Patent No. 3. Testifying as a witness in this action, Peterson said: — “However, the No. 3 Patent followed close on the heels of this early establishment of the use of No. 2, and No. 2 just about evaporated.” Por years, all of plaintiff’s own reinforcements, except dead ends, had been made under Patent No. 3, which plaintiff has maintained, albeit erroneously, covers all reinforcements with pitch lengths less than those of the strands of the cable. Under the state of the art after 1952 the manufacture and sale of the inventions of Patent No. 1 and Patent No. 2 was commercially unprofitable. Plaintiff was therefore bound to know that the large volume of reinforcements on which it was receiving royalties from defendant were made with a hand of lay the same as that of the cable and with pitch lengths less than those of the cables of association. In view of plaintiff’s acceptance of royalties under the above circumstances, defendant was justified fully in concluding that plaintiff consented to the manufacture and sale by de