66 Statement of the Case. ing a universal joint between them by means of an overhanging guard or bumper on the stern of the forward boat, with a central notch therein, into which the projecting stem or cutwater of the rear boat fitted." "My improvements," says the patentee, 'consist, first, in coupling and centring said boats together and forming a universal joint between them by means of a chain, the two ends of which are fastened to opposite points on the stern of the forward boat and the central part to the stem or cutwater, or some central point on the bow of the rear boat, so as to hold its stem or cutwater against the overhanging guard or bumper of said forward boat, said chain serving to centre the boats without the necessity of any notch in the overhanging guard for the stem of the rear boat to fit into, and at the same time coupling and holding the boats together and forming a universal joint between them; second, in attaching the ends of the coupling and steering chains to the boats by means of crow-foot claw-hooks so as to render the chains easily adjustable, as hereinafter shown and described." He claimed as his invention: "1. The combination of the two boats A and B, the steeringchain a passing around sheaves or pulleys, and around the windlass C, or its equivalent, the overhanging guard or bumper on the stern of the forward boat, and the chain D attached to opposite points on the stern of said boat and to the stem or central part of the bow of the rear boat, so as to form a uni⚫versal joint between them, and keep them coupled and centred, substantially as shown and described. "2. In combination with the boats A and B and the coupling and steering mechanism herein described, the claw-hooks hh, for attaching and adjusting the coupling and steering chains, substantially as set forth." Upon the hearing in the Circuit Court an interlocutory decree was entered in favor of the plaintiff, finding the validity of the patent, and the infringement by the defendant, and ordering a reference to a master for an account of the "profits, gains and advantages which the said defendant has received or made, or which have arisen or accrued to it" from the said infringement, etc., but denying the injunction upon the ground, stated Opinion of the Court. in the opinion of the court, McCreary v. Pennsylvania Canal Co., 5 Fed. Rep. 367, that its allowance would cause much greater injury to the defendant than benefit to the plaintiff. A large amount of testimony was taken before the master, who reported that he found no proven profits, savings or advantages to have been received by or accrued to defendant from the manufacture, use or sale of the plaintiff's patented improvements. Exceptions were filed to this report, and upon the hearing of such exceptions a final decree was entered in accordance with the report, and that the plaintiff should recover his costs, except the costs of the accounting before the master, and the costs of the exceptions to the master's report, which were awarded to the defendant. The decree was subsequently amended by ordering that the defendant pay all the costs of the suit. From the decree denying the recovery of profits and damages an appeal was taken to this court. Mr. Charles Sidney Whitman for appellant. Mr. S. S. Hollingsworth for appellee. MR. JUSTICE BROWN, after stating the case, delivered the opinion of the court. About three months prior to the patent in suit, and on April 16, 1872, another patent, numbered 125,684, was issued to Elijah and John McCreary, for "an improvement in steering devices for canal boats," etc., which covered a similar coupling together of boats, barges and scows by means of a vertical groove formed in the overhanging stern guard or bumper of the forward boat, which groove was entered by the cutwater of the rear boat, a chain being used for connecting the boats, which chain was so connected with a train of gear-wheels placed in the rear boat as to enable both boats to be steered by means of a windlass. The first claim of this patent was as follows: "1. Two boats or barges, A and B, fitted together by means of a projecting cutwater fitting into a notch in an overhanging guard, as described, and coupled and steered by means of a Opinion of the Court. chain or rope, having its ends fastened to the forward boat and passing around pulleys, substantially as herein set forth." The second claim was immaterial. In patent numbered 129,844 the patentee stated that his improvement upon the prior patent consisted "in substituting for the projecting cutwater and notch, described in said patent for centring the boats together, and forming a universal joint, a chain attached at both ends to one boat, and at its centre to a central point on the adjacent end of the other boat," etc. One of the main difficulties in the assessment of damages in this case arises from the fact that the two patents, the first one of which is not included in this bill, describe a system of coupling together two boats by means of chains and a centring device much the same—differing from each other only in two particulars: First, in the earlier patent, the two boats are connected together by the cutwater of the rear boat fitting a groove in the overhanging guard of the forward boat; while in the later patent, there is substituted for this a chain attached by both ends to the forward boat, and at its centre to a central point on the adjacent end of the rear boat. Second, in the later patent, the centre of the chain is wound around a horizontal windlass, while in the earlier it is wound around a separate wheel geared to the windlass below the deck-a difference which it was not insisted was material. In this connection, the master found that "the combination of the patent in suit and that of the prior patent are practically identical in function and result, and are identical in constitution, save only as to one particular element, the 'centring' device. As, therefore, the combination of the patent in suit is one, the sole invention and novelty of which consisted of a single element, the profit which complainant is entitled to recover from the defendant in this case is that which he may have shown to have accrued to it from the use of substantially that new element in substantially the combination in which he has described and claimed it." Exception was taken to this finding, upon the ground that the finding contained an "erroneous construction of law, Opinion of the Court. if it means that the complainant is not entitled to recover the entire profits which have accrued to the defendant from the use of boats containing the invention described and claimed in the patent in suit because of anything shown or described, but not claimed, in said prior patent of the complainant numbered 125,684." Plaintiff claimed, and offered evidence tending to show, that defendant had made a large sum in "savings" by the transportation of coal in its infringing double boats in place of single boats, and asked that defendant should be held accountable to him for these savings (less the cost of applying the couplings to the double boats) as its profits from the use of this improvement. The master found, however, in this connection, that complainant was not entitled, upon the proofs, to recover from the defendant as its profits from the use of his "improvement" the entire savings in freight accruing from the shipping of coal in the infringing coupled boats in place of single boats, but was restricted to such as were attributable solely to the improvement. There is no doubt of the general principle that, in estimating the profits the defendant has made by the use of the plaintiff's device, where such device is a mere improvement upon what was known before, and was open to the defendant to use, the plaintiff is limited to such profits as have arisen from the use of the improvement over what the defendant might have made by the use of that or other devices without such improvements. This is a familiar doctrine announced by this court in a number of cases. Seymour v. McCormick, 16 How. 480; Mowry v. Whitney, 14 Wall. 620; Littlefield v. Perry, 21 Wall. 205; Elizabeth v. Pavement Co., 97 U. S. 126; Garretson v. Clark, 111 U. S. 120. The important question in this connection is, whether, in considering what was already known, and open to the defendant to use, we are to include the device shown in patent numbered 125,684, issued to Elijah and John McCreary about three months before the patent in suit. There were other methods of connecting vessels in train, such as were disclosed in the British patent to Taylor of 1846; the British patent to Bourne Opinion of the Court. of 1857; the patent to McCreary of 1860, constructed and put into use upon a coupled boat called "The Experiment;" the British patent to Bartholomew of 1862; and the American patent to Stackpole of 1866: but none of these seem to have been adapted to defendant's use with any advantage over single boats, because, as the master found, "their construction was such that a rudder could not be applied to the forward boat." He found, further, that "these prior boats were in other respects inferior to the machines of complainant's patent, but their fatal defect for defendant's purposes was this inability to apply a rudder to the forward boat, which was therefore unmanageable when separated from its mate." There is nothing, however, to show that the device described in the patent of April 16, 1872, to the McCrearys, was not an operative device, and if it were open to the defendant to use, the plaintiff, in this action, would be limited in his recovery to the profits which the defendant made by the use of the improvement described in the second patent, over the device shown in the earlier patent. This improvement, as before stated, consisted principally in substituting for the projecting cutwater and notch, described in the earlier patent, a chain attached at both ends to one boat, and at its centre to a central point upon the adjacent end of the other boat. No attempt was made to distinguish or separate the profits arising from this improvement, the testimony being directed only to showing the profits defendant made by the use of coupled boats in the place of single boats. There was evidence tending strongly to show that the transportation of coal in double boats was more economically effected than in single boats, but none that the second patent was superior to the first. Indeed, the plaintiff admitted, in his argument, that the patent of April 16 described a plan of coupling and steering very little inferior to that described in the patent sued upon, and that, if defendant had pirated that invention instead of this, the same result in profits or savings would have been realized. Plaintiff, however, contended in this connection, that in determining the state of the art, or what was open to the defendant to use, the invention disclosed in the earlier patent to the McCrearys |