"The headers are serpentine in form, connecting the water-tubes 25 in single vertical series in staggered succession, or connecting the water tubes 26 in single vertical series of sub-groups or clusters in a similar staggered relation."

This means that a certain number of the lower tubes 25 (not numbered in the above figure, but being the tubes inclined from the front downwardly to the rear) are connected with a section of the front header, and with a corresponding section of the rear header, in such a manner that the tubes thus connected are arranged over one another (that is, in single vertical series), in a zigzag or staggered course, and that a certain number of the subgroups of the upper tubes 26 (not numbered in the above figure, but being the tubes inclined from the front upwardly to the rear) are connected with a section of the front header. and with a corresponding section of the rear header, in such manner that the subgroups thus connected are arranged over one another (that is, in single vertical series), in a zigzag or staggered course. It will be observed that the lower tubes 25 and the upper tubes 26

are oppositely inclined, and the specification says that "the opposite inclinations of the successive groups of tubes promote the reverse circulation." This statement, it seems to me, makes it reasonably clear that "the groups of inclined generating tubes in vertical succession, mentioned in claim 5, mean the oppositely inclined tubes 25 and 26, and not the inclined tubes 26 alone. There is nothing in the specification or drawings intimating a purpose to use in a boiler a group or bank of tubes inclined only as the tubes 26 are inclined. The claim of a patent must be read in connection with its specification. When the whole of claim 5 is read, it is found to relate to the larger tubes adjacent to the furnace and also to subgroups of small tubes, which latter the specification shows are above the larger tubes, and oppositely inclined to the larger tubes for the purpose of promoting reverse circulation. Claim 5 is for a combination. It is utterly impossible to understand it without reference to the specification. That reference, I think, shows that the larger and the smaller tubes shall be oppositely inclined, notwithstanding no such statement is expressly made in the claim. As all the tubes in the defendant's boiler are inclined in one direction, the defendant does not use the combination described in claim 5 of the Pratt patent, and consequently, does not infringe it. The Hoxie patent presents a very different question. The only drawing annexed to it is shown on opposite page.

The specification and claim are not long and are quoted in full, with numerals inserted at the beginning of each sentence for the purpose of convenient reference:

"Be it known that I, William D. Hoxie, a citizen of the United States, residing at Brooklyn, in the county of Kings and state of New York, have invented a new and useful improvement in steam boilers, of which the following is a specification. [1] Heretofore in this type of boiler the inclined water-tubes were set at an acute angle with the vertical face or front of the boiler-in other words, were pitched downwardly from the front to the rear--the combustion-space within the furnace being highest at the front and lowest at the rear portion. [2] This arrangement of the inclined water-tubes also left a vacant vertical space above the rear end of the tubes. [3] The present invention consists in reversing the inclination of the water-tubes-that is, directing them upwardly from the front to the rear at an obtuse angle with the vertical face or front of the boiler-thus increasing the capacity of the combustion-chamber of the furnace at its rear part and transferring the vacant space above the tubes from the rear to the front of the boiler, and locating the steam and water drum at the front within this space, whereby it and its attachments are rendered more accessible and convenient for use and the whole structure made more compact. [4] Another great advantage in this reverse arrangement of the water-tubes is that they pitch downward toward the front of the boiler, which enables them and their spaces to be readily cleaned, removed, or repaired from directly within the fire-room. [5] In the accompanying drawing a side elevation, partly in section, of a boiler is shown embodying the improved arrangement. A, A, representing the vertical headers: B. the intermediate inclined water-tubes; C. the furnace with its door. C'. and D the steam and water drum with its water-gage, d, these parts constituting the main essential elements in the structure, that are only necessary to refer to herein as explanatory of the appended claim. [6] By the construction and relative arrangement of the parts above enumerated and illustrated in the drawing it will be observed that the combustion-chamber of the furnace is enlarged at its rear portion, which allows the gases to expand and give out their full heating effect as they pass to the inclined water-tubes which form

the principal generating feature of the boiler, the gases being directed through and around the same by the use of well-known batlleplates and by the also well-known staggered arrangement of the tubes with respect to each other or to each vertical series. [7] The reverse inclination of the water-tubes is also of great practical importance with reference to placing, removing, or cleaning the same. [8] The ends adjacent to the fire-room are brought down within more convenient reach for handling, and in cleaning the natural tendency of the dirt is to gravitate toward the cleaner. [9] By this arrangement the steam and water drum D is located on the extreme front of the boiler, which renders it more accessible for inspection, setting up, or repairs, and its usual appendages, like the water and pressure gages, gage-cocks, etc., are brought within the nearest possible association with the attendant. [10] This new type of boiler is especially adapted for marine uses wherein a series of boilers are employed and which are frequently located upon opposite sides. within the hull of the vessel, the fire-room being located intermediate of the same. [11] Having now described my invention sufficient in detail as ex

planatory of the claim, I wish it to be understood that I desire to secure by Letters Patent the broad combination of parts as set forth in the following claim: [12] In a sectional steam-boiler of the type described, the combination with the reversed inclined water-tubes of a transverse steam and water drum, located at the front of the boiler in the space above said tubes, as shown and described."

The most obvious difference between the Hoxie boiler and the defendant's boiler is in the fact that the Hoxie boiler, as heretofore constructed, has had sectional headers, while the headers of the defendant's boiler are nonsectional. The conclusion has already been expressed, however, that the Hoxie patent is broad enough to include boilers with nonsectional headers. This difference, therefore, does not enable the defendant to escape an adjudication of infringement. But the defendant's counsel contend that the Hoxie patent is void because of alleged anticipations by other patents. This defense, in my opinion, is not supported by the proofs. The Dickerson reissued patent, No. 1,993, granted in 1865, has a drum, as the defendant's expert, Mr. Stuart-Smith, admits, that covers the whole top of the boiler. It is therefore much higher than the Hoxie boiler, and probably could not be placed in a modern war vessel below its protected deck; and the testimony of Admiral Melville and Commodore Isherwood, which is not contradicted, shows that when tested in two naval vessels shortly after the Civil War it proved to be a complete failure. The Pratt patent, No. 439,684, of November 4, 1890, one of the two patents now in suit, while it has tubes inclined upwardly from the front to the rear, has other tubes inclined downwardly from the front to the rear. It has also a longitudinal drum. The Pratt patent, No. 428,632, of May 27, 1890, and the Pressard patent, No. 432,075, of July 15, 1890, have tubes inclined upwardly from the front to the rear, but each of them has a longitudinal drum. The remaining patents cited as anticipations have tubes inclined downwardly from front to rear. In none of these patents is there "the combination with the reversed inclined water-tubes [that is, with tubes inclined upwardly from front to rear] of a transverse steam and water drum located at the front of the boiler in the space above said tubes."

It is further argued that Hoxie's use of tubes inclined upwardly. from the front to the rear was old, and that the transfer of the steam and water drum from its transverse position at the rear of the boiler, or from its longitudinal position, to a transverse position at the front of the boiler, involved no inventive genius. It must be admitted that Hoxie's statement in clause 1 of the specification-that "heretofore in this type of boiler the inclined water-tubes were set at an acute angle with the vertical face or front of the boiler, in other words were pitched downwardly from the front to the rear"-was not accurate. Dickerson's reissued patent, No. 1,993. Pratt's patent, No. 428,632, Pressard's patent, No. 432,075, and Pratt's patent, No. 439,684, all above referred to and all issued before the Hoxie patent, had reversed water-tubes. But I find no difficulty with this inaccurate statement of the prior art. If a patentee in his specification describes in appropriate language a real invention, and properly sets forth his claim to that invention, he is not to be deprived of it merely because

he has inadvertently erred in his reference to the prior art. The pertinent question is: Is the thing he described and claims an invention? The argument of the defendant's counsel is based on the assumption that the Hoxie patent must stand or fall "solely on the upward inclination of the generating tubes from front to rear." But the invention, as described by the patentee in clause 3 of the specification, is not so narrow. He there says that his invention.consists in reversing the inclination of the water-tubes, and in locating the steam and water drum at the front of the boiler in the vacant space above the tubes. These two things constitute his alleged invention, and they, in combination, are what he sets forth in his claim. Simple, very simple, the combination seems to be. But, so far as the record discloses, nothing like it was ever before devised. Some of the advantages of the Hoxie boilers are mentioned in the specification. Others are mentioned by the complainant's witnesses. The Hoxie patent seems almost to have revolutionized the art of constructing boilers for marine uses. Since 1897 Hoxie boilers have been installed in vessels of the United States Navy, aggregating 497,946 horse power, and in vessels of the navy of Great Britain, aggregating 291,850 horse power. In the vessels of all countries the Hoxie boilers ordered or installed now aggregate nearly 1,000,000 horse power. The Hoxie boiler combines compactness with safety, efficiency, durability, and great convenience in cleaning and repairing. It was introduced in the navy of the United States by Admiral Melville, while he was Engineer in Chief of the Navy, after examination of many other types of boilers offered to the Navy Department, and was selected by him because he deemed it "the best boiler of the class to be installed in the ships of the Navy of the United States." He declares that it has given "perfect satisfaction so far as the work of man can go," and that Hoxie was the first to solve the efforts of a hundred years to construct a light, safe, and economical marine boiler. Previous to 1897 the type of boiler principally used in the larger vessels of the United States Navy was the fire-tube boiler. Between 1891 and 1897 a controversy had been carried on in engineering periodicals concerning the relative merits for marine uses of fire-tube boilers and water-tube boilers. This controversy became known as the "Battle of the Boilers." These facts show how strenuous were the efforts before the date of the Hoxie patent to invent an improved type of marine boiler. In that battle Hoxie was the victor. The simplicity of the invention may cause surprise that the battle was so long a one. But the fact that there was

such a battle is conclusive proof that the combination described in the Hoxie patent was not obvious. In Loom Co. v. Higgins, 105 U. S. 580, 26 L. Ed. 1177, Mr. Justice Bradley, in considering the fifth claim of the Webster patent, then in suit, said:

"It is further argued, however, that, supposing the devices to be sufficiently described, they do not show any invention, and that the combination set forth in the fifth claim is a mere aggregation of old devices, already well known, and therefore it is not patentable. This argument would be sound if the combination claimed by Webster was an obvious one for attaining the advantages proposed-one which would occur to any mechanic skilled in the art. But it is plain from the evidence, and from the very fact that it was not sooner adopted and used, that it did not for years occur in this light to even 151 F.-18