Opinion of the Court 138 C. Cls. the base. Precast structural concrete blocks were then set on the waterproofing on the top of the base and spaced at intervals of about ten feet. Metal pipes or mains were then placed on top of the spaced blocks and temporarily supported by said blocks. Forms were then erected on each side of the base and lined with waterproof felt and hot pitch. Next, a slurry of heat-insulating concrete was poured into the forms around the pipes to a depth some six inches above the top of the pipes. The heat-insulating concrete was a mixture of Portland cement, vermiculite, a water-repellent admix and water, and had a density of about 23 pounds per cubic foot when set. After the insulating concrete set, waterproof felts were folded over the top of the insulating concrete and mopped in place with hot pitch. The trench containing the heat-insulating pipe system was then backfilled with sand and earth. In some locations where the underground pipe system was located under a roadway or aircraft runway, structural concrete slabs were installed above the underground system. Defendant contends that its use of concrete blocks to support the pipes during installation avoided infringement of the claims in suit. Plaintiffs assert that such blocks spaced at intervals along the pipes are temporary supports and that it is immaterial whether the initial support of the pipes while the insulating concrete is poured and sets be concrete blocks as used by the defendant or be suspension wires or chair-like devices as illustrated in the Goff patent drawings. While the Goff patent specification describes wires for suspending the pipes during embedment in the heat-insulating concrete, and also illustrates chair-like devices in figure 9 of the patent drawings, the pipe supports used during installation are not a detail of the claimed invention. The Goff claims in suit define an installed system rather than a method of installation or the supplemental structures used to aid in making the installation. We believe that the defendant's use of spaced concrete blocks to support the pipe during the installation does not warrant a conclusion that such blocks are the only support for the pipes after the insulating concrete has set and does not provide a sufficient distinction from the Goff patent to avoid infringement. 114 Opinion of the Court In determining whether an accused installation infringes a valid patent, resort must be had in the first instance to the words of the claims. If the accused matter falls clearly within the claim, infringement is made out and that is the end of it. Graver Mfg. Co. v. Linde Co., 339 U. S. 605, 607 (1950). Patent specifications and drawings are not to be read so as to limit the scope of the claim recital where the claim recital is clear and unambiguous. While claims should be construed in the light of the specifications and drawings to obtain an understanding thereof, the illustrative embodiments specified are not to be read into the claims. See White v. Dunbar, 119 U. S. 47, 51-52 (1886). The claims alone define what is covered by the patent. See Kuhne Identification Systems, Inc. v. United States, 82 C. Cls. 237, 258 (1936). We note that the contract under which the accused installation was made at McGuire Air Force Base specified that the underground conduit be formed of a mixture consisting of Portland cement, aggregate, admix and water in proportions substantially identical with the proportions taught by the specification of the Goff patent. The contract specified that the insulating concrete have a density of approximately 23 pounds per cubic foot. Claim 2 of the Goff patent recites that the insulating concrete weighs approximately 23 pounds per cubic foot. There is no question that the accused installation infringes upon the claims in the Goff patent. However, in those portions of the accused installation where a structural concrete encasement or preformed vermiculite planks were used to enclose the heat-insulating concrete, there was no infringement of the Goff patent invention. We conclude and hold, therefore, that claims 1, 2, 3, 5, 6, and 7 of Goff patent No. 2,355,966 are valid and have been infringed by the accused underground pipe system installed at defendant's McGuire Air Force Base, and judgment will be entered to that effect. The extent of liability will be determined in further proceedings before the Commissioner. It is so ordered. WHITAKER, Judge; LITTLETON, Judge; and JONES, Chief Judge, concur. Dissenting Opinion by Judge Madden MADDEN, Judge, dissenting: 138 C. Cls. I think the Government's structure did not infringe the plaintiff's patent. The essence of the plaintiff's discovery is that cell-concrete, though necessarily weaker than ordinary structural concrete, may, if mixed in the right proportions, be light enough to be a good insulating material, but heavy enough to bear the weight of the pipe without being crushed by that weight. The plaintiff's discovery thus makes it possible to eliminate the metal roller or rocker supports for the pipe which were thought to be necessary when the pipes were surrounded by a light substance such as mineral wool or cell-concrete. The court's opinion says that there was skepticism in the trade as to whether the plaintiff's discovery was practicable, i. e., whether if the cell-concrete was really made light enough to make good insulation, it would bear the weight of the pipes without crushing. If the Government's installation operates satisfactorily for 100 years, it will still prove nothing as to the practicability of the plaintiff's device. In it, the cell-concrete around the pipes does not bear the weight of the pipes. The pipes are rested on pre-cast structural concrete blocks at intervals of not more than ten feet. The opinion of the court speaks of these blocks as temporary supports. I see nothing temporary about them. They supported the pipe when it had nothing else around it but air; they would continue to support it if it had nothing else around it but mineral wool or saw-dust. When the cellconcrete was poured, the hard concrete blocks were embedded in it and will always be there. If the skeptics should, after all, turn out to be right, and installations resting only on cell-concrete should fail, after years of use, the Government's structure will not fail, because the pipes do not rest on the cell-concrete. They are merely surrounded by it. The most that can be said is that they would rest on it if they did not rest on something else, which they do rest on. The decision of the court seems to me to say that if there is an old, unpatented method of accomplishing a result, and a new, patented method, one is guilty of infringement if he continues to use the old method when, in the opinion of the 114 Findings of Fact patentee and the court, he could have accomplished the result by using the new method. If that is infringement at all it should be designated as constructive infringement, infringement not by use of the patented method, but by resort to a legal fiction. I see no good reason for resort to the fiction. FINDINGS OF FACT The court having considered the evidence, the report of Commissioner Donald E. Lane, and the briefs and arguments of counsel, makes findings of fact as follows: 1. This is a patent suit arising under the provisions of 28 U. S. C. § 1498 for the alleged infringement of United States Letters Patent No. 2,355,966, issued to Universal Zonolite Insulation Company on August 15, 1944, on an application for patent filed May 20, 1942, by David C. Goff. The Universal Zonolite Insulation Company, a Montana corporation, by amendment of its articles of incorporation, changed its name to Zonolite Company on December 18, 1947. Plaintiff Zonolite Company has been the owner of legal title in and to said patent in suit since said date of issue. Plaintiff Insulating Concrete Corporation, a Virginia corporation, is exclusive licensee under said patent for a territory including the place at which the alleged infringement occurred, namely, McGuire Air Force Base, Wrightstown, New Jersey. 2. The parties agreed at pretrial to a separation of issues for trial, and that the issues of validity of the patent and of infringement of the patent by the defendant be first determined upon full proofs, findings of fact, and argument of counsel. The two plaintiffs were represented at the trial by the same attorney. 3. The general subject matter of this suit relates to underground insulated pipe systems for conveying heated fluids, generally steam or hot water, between a boiler plant and other buildings in which the fluids are to be utilized for heating or the like. To be satisfactory for such use, underground insulated pipe systems should insulate the pipes against heat loss, protect the pipes from physical damage by external forces, permit the pipes to expand and contract in Findings of Fact 138 C. Cls. response to changes in the fluid temperatures, and should protect the pipes against external moisture and corrosion. THE PATENT IN SUIT 4. The patent in suit, No. 2,355,966, hereinafter referred to as the Goff patent, discloses in its specifications an underground insulated pipe system, and includes drawings illustrating embodiments of the invention. The Goff specifications state: *** the present invention involves the employment of a new type of light-weight heat-insulating concrete, which permits of an improved outstanding procedure and substantially better resulting structure, such concrete including a light-weight aggregate expandedvermiculite which possesses properties unusually well qualifying it for the purpose indicated. Whereas the proportions of the ingredients of such light-weight heat-insulating concrete may vary as circumstances indicate, a suitable mixture for use under ordinary conditions would be 1 bag of Portland cement (about 94 pounds), 8 cubic-feet of expanded-vermiculite (minus 10 plus 65 mesh), 7 quarts of Admix and 26 gallons of water; such Admix comprising a suitable asphaltemulsion, * * * The novel heat-insulating system is unique in that the thus formed insulation is poured monolithically around the pipe or pipes which are to convey the heated fluid or to conduct the returning condensed steam, for example, and, in this way, the hollow clay-tile, or metal-casing conduit, with its tendency to breaks and the essential joints and costly laborious methods of installation are eliminated, the new concrete being poured around the one or more pipes and allowed to dry, whereupon the entire surface thereof is waterproofed as by 15 pound felts and pitch or asphalt. This insulating-concrete has sufficient structural strength that pipes may be embedded within the mass and their position maintained thereby indefinitely without the use of pipe roller or rocker supports, although these may be employed if desired. The special properties of the new concrete affords [sic] the mass great elasticity, workability, and plasticity, and, in addition, tests show that it can be subjected to a 100 cycle of freezing and thawing without |