not remove the lateral support of adjoining land in its natural state, he may do so as to artificial structures, provided he uses ordinary care. This is the common law. But in a large city a builder cannot afford to stand on his common-law right. Business necessity and the convenience of his neighbors, his own power to proceed uninterruptedly with his building, the probability of litigation over the vexed question of ordinary care-always a troublesome question, and one immensely difficult in lateral support cases-all combine to influence him to find some means of sustaining adjoining structures while proceeding with his own. Indeed, it has become the general if not universal custom in large cities for builders to do this, and contracts for large buildings commonly so provide; so the necessity in building operations in large cities for some practical means of sustaining adjoining buildings is apparent. Another important element of the problem is the deep basement, lately made more important by the construction of the Chicago Subway.

The problem of lateral support in building operations has always been an important and difficult one, and it was partly solved more than a hundred years ago. In 1803 the center-core system, as it has been called, was used on the Tronquoy Tunnel in France, and has been ever since employed in some form. This system is the leading feature of the Ewen patent, and has long been applied to parallel longitudinal trench open-cut tunneling. Its simplest illustration is a street subway. Two parallel trenches are dug, one on each side of the street. These are lined with planks or timbers, braced with pieces of timber to prevent caving. The middle of the street is the center core. A stone wall is built in each trench, girders laid from the top of the walls to a column set in the street center, and the street surface constructed upon the girders. The core of earth is then removed, and the tunnel complete. This description is not technically accurate, but good enough to illustrate the plan of overcoming lateral pressure by the center-core system, with its trenches, trench linings, and braces, the girders finally taking the place of the core. It was employed in the great Boston subway, built in 1896 and 1897, and was fully known to the inventor when he conceived his invention in 1902. The system is completely described in the Goodredge patent of 1882, No. 262,403, except that sheet piling or plank driven into the earth, edge to edge, is used to line the trenches, without braces; was applied to a single trench by Friestedt, in his patent of 1890, No. 435,492, for supporting and lowering building foundations; and the feature relating to the use of linings and extensible braces is covered by the McKiernan patent of 1873, No. 145,116. Some features of the system also appear in other illustrations of the prior art, among others the Washington patent of 1900, No. 654,426. It was also employed on the east wall of the Tribune Building in Chicago in 1901, where a rigid wall was constructed on the outside of the wall trench, and a flexible lining on the inside against the earth core, the space between the two being braced by jackscrews. This is shown by the following cut:

It was the Tribune building, the first deep-basement construction ever put up in Chicago, and the difficulties experienced in building it, which led the patentee to study the subject of subconstruction, and resulted in his application for the patent in suit in 1902. It is now insisted by the patentee that his improved system was never used in building operations or elsewhere, prior to his application, was never conceived, understood, or intentionally applied by anybody, and had never in any way been anticipated. His process may now be described.

It is nothing more than a simple application of the center-core system to the skyscraper deep-basement problem, with some improvements of process which are said to be vital. The patent is for a process, an operation done by rule to secure result, or a mode of treatment of materials producing a result. It is not a machine, device, or function of a machine, but simply a method of doing things. A trench is dug to any desired depth on two or four sides of a proposed building, and in place of the removed earth linings and jackscrews are substituted to hold the trench walls in place, and thus interpose as nearly as possible the same resistance to lateral pressure as existed before the trenches were dug. Walls are then built in the trenches, continually braced meanwhile by the adjustable jackscrews, against the center core on one side and the adjoining property on the other, so as to constantly maintain the requisite resistance to lateral pressure, and thus prevent settling, and finally the walls are braced on the inside by basement floor girders, and the earth core removed.

From this general description it will be seen that so far nothing appears to distinguish the process from the center-core system used a hundred years ago, except it is employed for a new purpose. But from a more specific description a number of other features, claimed to be essential parts of the process, will appear. From the description and claims of the patent and the testimony in explanation of it, the mode of operation, more in detail, is as follows: Around the whole building site, with heavy buildings on two or three sides and across the street, a trench is dug of any desired width, one foot in depth according to the patent, and five feet deep in practice. This trench is not commenced at the street level, but it is customary in applying the method of the patent to dig out the earth under the proposed new building down to a point opposite the footings of adjoining buildings, as this may usually be done with safety, meanwhile shoring their walls. The trench is then dug five feet deep and eight or ten feet wide all around the site. A sheath or lining of planks is set up endwise on each wall of the five-foot trench around the whole site. Crosspieces called "walings," about 12 feet long, are then placed crosswise on each lining, and are held in place by jackscrews, thus dividing the lining into loose sections 5x12 feet. The planks are not fastened together, nor are the walings fastened to the plank linings in any way, but the planks are generally matched staves so as to make a tight connection. The banks of the trench are sustained and braced by the operation of the jackscrews

against the crosspieces or walings, the screws being kept tight by manipulation where necessary. The lateral thrust or pressure from the earth outside the trench is thus taken up by the center core, just as in the old system, and the screws or braces kept tight. This process is repeated for the next five feet, and so on until the desired depth is reached; but variation in the conditions may require a variation in the process.

It is easily seen, if the soil is as described by the witnesses, composed of plastic clay, with quicksand pockets, full of strata containing water and gas, that, when the trench is dug out near the footings of a heavy building, the gas, water, quicksand, and mud are liable to come out into the trench, even before the lining can be adjusted, and also be forced up from the bottom of the trench by the lateral thrust. Water will also at first run through the cracks of the lining between the lining planks unless matched staves are used, as in the County Building. This soil movement will allow the adjoining buildings to settle to some extent, and even buildings from half a block to a block distant may be slightly affected; and it will displace the soil in the outer banks of the trench, and affect the pressure there localized.

It is at this point that the alleged invention appears, the part of the process not used in the prior art, and which is the one discovery claimed by the patentee. The discovery is said to be this: that it is found, if the jackscrews be constantly manipulated and kept tightly screwed up, and the movable sections of the linings of the trench, approximately five feet by twelve, be kept firmly pressed against the trench walls, a constant and even distribution of the lateral pressure from the earth outside the trench, through the jackscrews to the supporting core inside the trench, will be maintained, and the adjoining buildings protected from substantial injury. Other constructors and inventors, in considering the solution of the problem, had, it is said, fixed their attention on the adjoining building, and had attempted, by shoring, piling, and other like devices, to hold it up. Ewen, on the other hand, regarded only the earth, and the feasibility of preserving the lateral support of the center core, existing before the trench was begun, and, so far as possible, maintaining original conditions. This is stated by complainants' counsel as follows: "To excavate this core or open a trench for the substructure, it is necessary to uncover one side of the building support, and this results in: First, a tendency of such support to move bodily or en masse toward the excavation; and, second, a tendency of the earth support to flow, to change its nature, structure, density, and. in short, its character, as a supporting medium (giving away in detail), and thus let the building sink and crumble, although it may not fall into the excavation.

"Either of these tendencies will wreck the old buildings, and hence must be resisted. With buildings light or far removed from the trench or with a shallow trench, the first tendency is easily resisted, and the second is negligible, but no one before Ewen had ever overcome the first tendency under the conditions of the problem, and no one had ever appreciated or tried to overcome the second tendency under any conditions."

This use of the thin lining, called the "floating" or "flexible" lining, and this constant operation of the jackscrews, are claimed to

be the two vital features of the invention, which distinguish it radically from the prior art. If Mr. Ewen is really entitled to them, I should have little hesitation in sustaining his patent. The art is a most difficult and important one, and any person who can find a process for safely sustaining lateral pressure in the business district of Chicago and other large cities is certainly entitled to all the benefit afforded by the patent laws. I am inclined to think he did discover them, without himself knowing it, but that he never fully understood. or claimed them, and that his discovery has become public property. It seems clear from the specifications, from Ewen's advertising matter, and his actions, that he never fully understood his system, although he knew enough to vaguely describe it. Thus, in the specifications, discussing the work at a stage when the trench has been fully completed and sealed up, and the wall built, he says:

"Obviously up to this point the conditions of stress and pressure between the exterior of the proposed building and the core of earth on the site of the building are practically undisturbed, and whatever weight there was on the exterior, as, for example, the weight of some building, is properly sustained against the core of earth within the building site. The pressure is taken up by the jackscrews, and then by the shorter jackscrews which act through the vertically arranged I-beams."

How this could have been written by an able and experienced engineer, describing his own patent, understanding that the danger point, the cutting of the trench, had long since been passed, is difficult to understand. Further than this, the operation of the jackscrews is not mentioned as a part of the process while that is being described, but is stated as a result, following from the necessary operation of the process. Thus, after fully describing how he does it, but without saying anything about the flexible lining or manipulation of jacks, he says it is obvious that the substructures may be carried downward to any desired depth, because the inner core carries the same load and sustains the same pressure all the time; but how or why it does so is not explained. Then a sort of parenthetical clause is thrown in, to the effect that jackscrews are used (instead of rigid braces, supposedly) because they are adjustable, and in large buildings (not in small buildings or medium-sized buildings surrounded by skyscrapers, but only in large buildings, no matter what the weight on the adjoining property) would be constantly attended and operated so as to keep the condition substantially uniform. Of course, the size of the building being erected is not an important factor, but the weight on the adjoining soil. All this loose talk in the specification shows how little the inventor really appreciated or understood his own invention. When we come to the claims of the patent we find even less to suggest these vital features. They are twelve in number, and contain a page and a half of closely printed matter, but not one of them has any suggestion of the flexible lining or constantly operated jacks. All but one of them call for trench linings and braces between them, "so as to transmit the exterior pressure to the core of earth within such proposed wall," but nothing more. Claims 2 and 10, relied on as infringed, are as follows: