so that the working side-strain falls mostly upon the outer end of the suction pipe (or of the ladder supporting said suction pipe, if such be used), and but lightly upon the joints or trunnions supporting the inner ends of said pipe or ladder. As the outer ends of these lines wind upon the drums in the device shown, the inner ends unwind and descend to the hold. The office of these lines is to swing the excavating apparatus or the dredger from side to side in the process of dredging, and firmly to anchor the excavator end of the dredger when it is not at work, which latter is accomplished by simply engaging both drums, h, h, in their friction couplings.

"N is a force and suction pump. It is used to exhaust the water from the discharge pipe for the purpose of raising the submerged portion, to dilute the spoils, so that they will spread over a large area of land, or to enable them to be transported through long pipes without the aid of a relay pump, to clear the pipes when accidentally choked, should this ever occur, and to prime the pump B; the latter or its suction pipe being provided with the usual valve or valves for that purpose. Like most steam pumps, it is provided with two suction orifices on opposite sides of the water chamber, and a discharge directly over each suction. To the suction and discharge on one side is connected the branch pipe O, leading into the pipe C. Each branch is provided with valves in the usual manner of arranging a branch pipe to serve for suction and discharge. The discharge branch only is shown, the suction being directly under it. To the suction on the other side of the water chamber is secured a valve and pipe communicating with any suitable supply of water (usually that in which the dredger floats), and sometimes by a branch pipe and valve with the hold of the vessel for discharging leakage, and by another branch and valve, with pump B, for priming said pump by suction. To the discharge above this suction is connected a pipe or hose, that may also be used for priming the pump B by discharging into it, and for all the various purposes of an ordinary ship pump. When O is used as a suction pipe to draw from pipe C', the valve on the discharge branch is closed, the suction-branch valve is opened, and the discharge is through the pipe or hose on the opposite side. When O is used as a discharge pipe to force into pipe C', the suction-branch valve is closed, the discharge-branch valve is opened, and the suction is through the opposite suction pipe. When the suction is through the pipe opposite the suction branch of pipe O, the discharge may be through the pipe or hose above it, or through the discharge branch of O into pipe C', as regulated by the valves to suit the purposes of the user.

"O is a pipe with branches and valves connecting both suction and discharge on one side of the pump N with pipe C', and is either a suction or discharge pipe, as regulated by its valves.

"P, P, are long, narrow, hollow floats, preferably extending longitudinally along each side of the short sections of the discharge pipe, for supporting them on the water. They may be made of wood or metal, and be secured together and to the discharge pipe by pieces of scantling passing crosswise over and under the pipe and floats, and fastened with rods passing each side of the pipe and floats, as shown in Fig. 11, though I do not confine myself to this form of construction.

"Q is a pulley or gear for actuating the gears, i, and excavator, E. be connected with its shaft by a friction coupling.

It may

"R is the driving shaft of the bucket wheel. It is keyed or otherwise secured to the hub of the wheel, whence it passes through suitable bearings in the inner chamber, up the suction pipe, and through a stuffing box to the gears, 1, by which it is actuated.

"S is a strong detachable steel knife, sometimes used on the edges of the buckets when working in hard material. It may be serrated, chisel-toothed, or straight-edged, according to the character of the materials to be cut, a straight edge being preferable for ordinary work.

"T is an inner chamber or shield, around which the bucket wheel revolves, and into which it discharges. This chamber is provided with a strong flange, by which it is secured to a similar flange on the end of the suction pipe. It is also provided with a large opening, a, Figs. 4, 7, through which the spoils

enter from the buckets, and through this opening, Fig.4, is seen a portion of the driving shaft, R, and the bearing of said shaft in the end of said chamber. This chamber or shield forms a bottom for the buckets, k, until they reach the opening, a, as shown in the cross section of the wheel and chamber, Fig. 7. As the buckets pass this opening, they discharge mud and water into the chamber, as indicated by the inner arrows, the outer arrow showing the direction of rotation. The office, in part, of this chamber or shield, is to prevent too large a percentage of water from entering with the mud; but when the spoils are of a character to require a large percentage of water to carry them up the suction pipe, or to send them through the discharge pipe, as may sometimes be the case, the chamber may be cut away until only enough remains to support the excavator and shaft, R.

"U, U, are blocks anchored at suitable points on each side of the dredger, through which pass the warping lines, M, M, for the purpose of swinging the dredger or the excavating apparatus from side to side. They are usually placed from three hundred to six hundred feet apart, and a little in advance of the ends of the first cuts made by the excavator, to allow a wide swing, and avoid the necessity for two frequent change of place as the work progresses.

"V is a branch pipe and valve, through which samples of the spoils are drawn from the discharge pipe, to enable the operator properly to regulate the speed of the side feed. It is preferably placed about one-third the diameter of the discharge pipe from the lower side of said pipe, in order to secure a fair average sample.

"W is a small tank resting upon scales. It is provided with a discharge pipe and valve. It is filled with spoils drawn from the discharge pipe through the branch and valve, V, and the speed of the side feed is increased or diminished according to the weight of the spoils.

"X is a floating mud receiver carrying the relay pump or other auxillary discharging apparatus, B', and its actuating apparatus. The main purpose of this receiver is to permit the excavator to run continuously, although the relay pump be stopped for a little while, the receiver affording a receptacle for the spoils in the meantime. Longitudinally through this receiver passes the pipe C" to the auxiliary discharging apparatus, B', whence the pipe C2 extends to another auxiliary discharging apparatus, or to the place of deposit. "Y is a valve on the pipe C", within the receiver, X. This valve is adjusted to open automatically outward with slight pressure, and serves as a relief valve in case of stoppage of the pump B' while the pump B is running. It serves also as a guide to regulate the speed of pump B', which should be increased beyond that necessary for preventing the opening of this valve in order to aid by suction as well as forcing. This valve may be set wide open for the purpose of filling the receiver, and may be securely closed when the pump B is used to force the material into the pump B' for the purpose of increasing the efficiency of the latter. It is also opened to admit air into the discharge pipe when the water is to be withdrawn therefrom by pump N.

"Z is a branch and valve through which mud is drawn from the receiver to be discharged through the pipe C2.

"Z' is a branch and valve for admitting water to wash out the pipe C2 after the mud has been discharged from the receiver.

"Z2 is a valve for closing the pipe C" while the mud receiver is being discharged, or when said receiver is disconnected from the pipe C', and takes the mud directly from the dumping or dredging apparatus.

"Z3 is a pipe and valve used for admitting water through the bottom of the receiver for the purpose of diluting the mud when it is too stiff to pass freely up the branch Z. It may have branch pipes with numerous small openings for the more thorough dilution of the spoils. This receiver may be used in connection with any dredging apparatus for continuous transportation of the spoils through pipes as the work progresses; or it may be filled, towed to the place of deposit, and there be connected with a discharge pipe for putting the spoils on shore.

"The operation of dredging is as follows: The vertical anchors and excavator being raised to allow freedom of motion, the dredger is placed in position with the turntable in line with the longitudinal axis of the proposed cut. The turntable is then rotated until the vertical anchors are also in line with said axis, and both anchors are then dropped into the mud. The discharge pipe is placed in position, the blocks, U, U, anchored at suitable points for swinging the machine, and the dredger swung around until the excavator reaches the side of the proposed cut, as shown in Fig. 10. The lines, M, M, are drawn taut, and the excavator lowered below the surface of the water. The pump B is then primed, started, and the excavator set in motion, and lowered its entire diameter into the mud. The proper winding drum is then engaged, and the dredger, swinging on the turntable as a pivot or center of oscillation, rapidly cuts its way to the opposite side. To secure a steady side feed, the friction coupling of the unwinding drum may be adjusted to keep the unwinding line sufficiently taut to prevent the veering of the dredger with wind or tide. Upon reaching the opposite side, the winding drum is disengaged, the excavator again lowered its full diameter, the side feed reversed, and the dredger cuts back again. This process is repeated until the proper depth is obtained. The excavator is then raised above the bank in front, the anchor G raised, as shown in Fig. 2, and the turntable rotated upon the anchor G2 until G is squarely in front of G2, in line with the longitudinal axis of the proposed excavation, as indicated by the broken-lined outline G', Fig. 2. G is then dropped into the mud, and the work proceeds as before, the dredger having been fed forward the distance between the centers of the vertical anchors, which is fixed to correspond with the cut capable of being made by the excavator. This arrangement for feeding forward keeps the center of oscillation of the dredger coincident with that from which the arc to be cut by the excavator should be described. A less perfect forward feed is secured by placing the dredger so that the excavator is at the side, and the turntable in line with the longitudinal axis of the proposed excavation. The turntable is then rotated until the vertical anchors are in a line parallel with the transverse axis of the dredger where it is made stationary. This leads one anchor diagonally in advance of the other, the dredger lying diagonally across one-half of the line of the proposed excavation. The forward anchor is now dropped into the mud to form a pivot, upon which the dredger swings as it cuts to the opposite side. The dredger then lies diagonally across the other half of the line of the proposed excavation, the swing having brought the rear anchor to the front. This anchor in its turn is dropped to form a new pivot, and the other anchor is then raised. The dredger swings first upon one and then upon the other anchor, these anchors being alternately raised and lowered for this purpose. As this mode of feeding by swinging alternately upon two different pivots gives a wedge-shaped cut, requiring two full swings to make one full cut, it is equivalent to a loss of one-half of the time, and is used only to prevent stoppage of work when the apparatus for rotating the turntable is stopped for repairs or other cause, in which case it becomes valuable."

It will be seen from the foregoing that the fundamental elements of the complainant's patent 318,859, and of the machine covered by it, are a boat and excavator capable of working with a side feed, a nonrotating suction pipe, an exhausting and discharging apparatus, a discharge pipe, a self-contained pivot or center of oscillation, on which the boat swings from side to side while it is working, devices for swinging and for working the machine from side to side, devices for moving the machine ahead preparatory to a new cut, a floating discharge pipe when the spoil is to be transported over water, a submerged discharge pipe when the spoil is to be carried across a navigable channel without impeding navigation, and an outer stationary section of discharge pipe when the spoil is to be carried over land.

The claims of this patent found by the court below to have been infringed by the defendant are the following:

"(10) A dredge boat having a self-contained pivot forming a center of horizontal oscillation, with devices for swinging and working said boat upon said pivot, in combination with a suction pipe, exhausting apparatus, and rotary excavator."

"(16) A dredge boat and oscillating section of a conduit discharge flexibly joined to a nonoscillating section to allow said boat to feed forward, and said oscillating section to swing upon the flexible joint connecting said oscillating and nonoscillating sections."

"(25) A discharge pipe consisting of a series of sections flexibly joined together, and supported by floats, in combination with a dredger having a rotary excavator."

"(53) The combination, with a nonrotative suction pipe, of a rotary excavator having an inward delivery through said excavator.

"(54) The combination, with a dredge boat and nonrotative suction pipe, of a rotary excavator having an inward delivery through said excavator." "(59) A rotary excavator with inward delivery, in combination with a nonrotating suction pipe mounted upon strong trunnions or equivalent joints, to permit the excavator and outer end of the suction pipe to be raised and lowered to suit the depth at which the work is progressing."

We

The defendant contends that the complainant was not the inventor of the machine thus patented to him, but that he copied its essential features from a machine built and invented by the defendant; and, moreover, that the complainant's machine was anticipated by various other patents and publications set up in the answer. If the evidence shows this to be true, we need go no further with the case. therefore turn to the record to see what foundation, if any, there is for this contention. So far as the defense of anticipation is concerned, it must be established as of a date anterior to the patentee's invention or discovery; not merely prior to the application for, or the date of, his patent. Rev. St. §§ 4886, 4920; Plow Works v. Starling, 140 U. S. 198, 11 Sup. Ct. 803; Clark Thread Co. v. Willimantic Linen Co., 140 U. S. 492, 11 Sup. Ct. 846; Loom Co. v. Higgins, 105 U. S. 592; Kneeland v. Sheriff, 2 Fed. 901; Woodman v. Stimpson, 3 Fish. Pat. Cas. 105, Fed. Cas. No. 17,979; Merw. Pat. Inv. § 323. And, as against the defense of anticipation, it is well settled that the patentee may show, if he can, the fact of invention by drawings, sketches, models, or any other competent proof. Walk. Pat. § 70; Loom Co. v. Higgins, 105 U. S. 594; Bates v. Coe, 98 U. S. 34; Smith v. Vulcanite Co., 93 U. S. 486; Apparatus Co. v. Woerle, 29 Fed. 451. The record shows that for many years the complainant was investigating the subject of dredging, and had familiarized himself with most, if not all, of the dredgers in existence. He was familiar, too, with the sand pump. The latter, while it would pump sand, would not cut and remove hard material. Before the complainant did anything in the direction of invention, there were also dredgers in existence and in use that would cut and remove hard material. There were the "Scoop" and the "Clam Shell," and the "Chain Bucket," and Hart's dredger, and Fraser's dredger, and the patent to D. S. Howard of January 9, 1855, and Atkinson's patent of July 7, 1863, and the

rotary-wheel dredge of Fondé and Lyons, and other rotary dredgers of which the complainant had knowledge; for in the original specification contained in his application for a patent he himself stated that "for more than two centuries rotary dredges have shown a capacity for cutting and lifting far in excess of any other dredging device; but in the forms of construction hitherto adopted it has been necessary to make the diameter of the wheel much greater than the depth to be dredged, thus making them too unwieldy for ordinary uses, while the best appliances for removing the spoils have fallen far short of the dredging capacity of the wheel." But, prior to the complainant coming into the field, there was no machine, by whatever name known, that would, by the simultaneous and continuous co-operation of its various elements, cut and remove hard material from a waterway, and itself transport the same to any desired distance and place. complainant undertook to accomplish that thing. The accomplishment of the purpose necessarily involved the severing of the material in place, the lifting of it, and its transportation through some sort of conduit to the desired place of deposit.

The

The evidence shows that the complainant, having devoted much study and thought to the subject, embodied his ideas in a drawing, marked "Exhibit DD," and which was introduced in evidence. Upon its face, the drawing is dated July 13, 1864. Counsel for the appellant assert in argument that this date is false; that the drawing was actually made in the year 1884, and antedated 20 years. The ground of this contention on the part of the appellant is that the words "inward delivery," which appear upon Exhibit DD, do not appear in the complainant's proceedings in the patent office prior to March, 1884. The words "inward discharge" appear, instead, in the complainant's original specification. The two expressions mean one and the same thing. The use of the word "discharge" in place of the word "delivery," in the original specification, is explained by the complainant by saying that the first draft of the specification was prepared by his attorney, who used the term "inward discharge" instead of "inward delivery," and that, when he (the complainant) revised and redrafted the specification before sending it to the patent office, he followed the phraseology of his attorney, but that subsequently, when he took personal charge of his application, he redrafted the specification and claims and adopted the phraseology originally used by him in the drawings of 1864. There is nothing in the circumstance relied on by the appellant to cast any doubt upon the testimony of the complainant in respect to the true date of Exhibits DD and EE, especially as there is much testimony corroborative of that of the complainant, which is to the effect that he made the drawing on the day they, respectively, bear date.

The complainant testified that, while holding a position as clerk in the office of the United States surveyor general for the state of California, he was thrown in daily contact with all matters pertaining to swamp land and swamp land reclamation, and had many conversa