Upon the hearing of this case upon the merits, it was adjudged by the court that the patent to the plaintiffs, dated August 8th, 1871, was a valid patent, and that the defendants were infringing in respect to all the pumps manufactured and sold by them subsequent to that date. It was referred to a master to ascertain and report the complainants’ damages. The master reported that the complainants should recover damages on 298 pumps manufactured, to the amount of $47.71 per pump. To this report the defendants filed exceptions, and the case now comes before the court on the hearing of such exceptions.
The principal question arises upon the third exception, and regards the rule for the measure of damages adopted by the master. The complainants proved the expenses of making .and selling the pumps in question, that they were prepared and ready to fill the orders taken by ■ the defendants, and the prices at which the pumps were sold by the defendants. The master found the damages to be the difference between such expenses and .such prices, and.reported accordingly.
if the plaintiffs had been the inventor and patentee of pumps, or of double-acting pumps, the argument would have been strong in favor of the rule adopted. ‘ But the invention patented and infringed was of an improvement •upon pumps merely. Such • was. the decree, which did not restrain the defendants from making pumps, or even the pumps in question, but only certain devices, forming a part of them, and which devices thecourtadjudged to be an improvement belonging to the plaintiffs, which had been infringed by the defendants. The decree adjudges that the letters patent in question, “for an improvement in gas pumps, dated August 8th, 1871, and more particularly set forth in the complaint, were and are valid in law, and that the defendants infringe on the rights secured thereby;” and the defendants are restrained “from making, using or vending the device or improvement secured thereby.” In making the report, his master says: “While admitting, of course, the doctrine that, in some cases, the profits resulting from the mere improvement must be separated from those of the entire machine, and allowed to the plaintiff as the sole measure of damages, I am unable to see how, upon any correct principle, this separation can be made in the present case. I have said, in the opinion accompanying this report, that, as it appears to me, the comparison must be made between the machine as it stands, with its patented improvements, and what would be left of the same machine, if these improvements were taken away, and not between this machine.'with its patented improvements, and any other one having the same general character, not patented, and used in the business, and sold in the market. If this criterion is the correct one, and, for the purposes of this decision, I hold it to be so, it is very plain that, if the patented improvements on this gas-pump are removed, there is nothing left which can be called a machine, and in respect of whieh any profits can be predicated. I distinctly hold, then, in order that the question may be distinctly presented —although it seems to me to be a matter of law, a sort of construing the machine in the *881same way that a court construes a writing— that the profits resulting from the patented portion of this pump cannot be separated from those resulting from any other part of it.” In concluding his report, he says: “In conclusion, I find and report, that the plaintiffs are entitled to recover, as ‘damages’ sustained by them, by the sale of the aforesaid 298 pumps by the defendants, as aforesaid,- at the rate of $47.71 for each pump so sold by the defendants, that being the whole profit which, as appears from the evidence, the plaintiffs would have made from the sale of each entire pump.”
Pumps have been in use since the earliest ages of the world. Double-acting pumps, like the one in question, have long been in use. Double-acting pumps, having cast a side chamber, to- allow the medium to follow the action of the plunger, have long been in use; and, in this, patent, it is expressly stated that this is not claimed as an invention by the plaintiffs. The base, the cylinder, the top, the piston, are the same, in general arrangement, as are used in ordinary double-acting pumps. These things are not claimed by the plaintiffs to be within their improvement. Their use Is free to the defendants. Only a special construction of the side chamber is claimed, whereby the same is adapted to use with the valve casings bolted on the outside. Valves must exist in every pump, and they must open on the outside. They are located in hollow casings, but this the inventor, in his patent, says that he does not claim. A valve-box or valve-case, (that is, the portion of the passages to and from the cylinder that contains the valves, cut off from the rest, for the convenience of fitting the valves, and then bolted on again to the outside of the cylinder,) is a valuable device, forming a part of this machine, but it is not claimed to belong to the plaintiffs, although the specification is said to have been drawn with reference to it. I do not pursue the analysis of the patent so carefully carried out by the defendants’ counsel, showing all the parts which were in use before the alleged improvement, and showing specifically what the patent claims. Enough has been said to present the main question in the case, viz., whether the patentees can recover the profits for the manufacture of the entire pump, or whether their claim is limited to the profits upon the improvement embraced within the patent. The master concedes the latter to be the rule in some eases; but, if I understand his reasoning, above quoted, he takes this case out of it on a ground that, I think, cannot be sustained. The comparison is to be made, he says, “between the machine as it stands, with its patented improvements,” (the plaintiffs’ improvements, I assume,) “and what would be left of the same machine if these improvements were taken away, and not between this machine, with its patented improvements, and any other one having the same general character, not patented, and used in the business, and sold in the market.” The portion of the pump in question which belongs to or is included in the improvement of the plaintiffs is very small, and a machine constructed upon other known principles and devices applicable to pumps, omitting the plaintiffs’ improvement, would include nearly everything useful that is to be found in the present machine. A different view of this matter of fact is the basis of the master’s opinion. I judge that the master holds the plaintiffs’ improvement to be more extensive than it is.
The proposition is simply this: The pat-entee takes the well-known portions of a pump used in pumping. gas-oil, with pas? sages, valves, piston, chambers, openings, &c., as ordinarily made and used, and adds a chamber of an important construction, as it is alleged, and a combination with certain other parts described. Now, if this addition is not a new and useful improvement, no damages can be claimed for its use. If it is such an improvement, the improvement, in its nature and by law, is and must be capable of being described and pointed out, and must be described and pointed out. Every skilful mechanic must be able to learn, from the patent itself, precisely what the monopoly covers. Act July 8, 1870, § 26 (16 Stat. 201). If this alleged improvement is so confounded with portions of the machine which are the subjects of other patents, or which, from long continued use, are open to the public, that it cannot be separated from them, or if, when so separated, it has no value, it is not a patentable invention, and no damages are due for its use. The decree in this case has adjudged the patent to be valid. In its nature, therefore, it is, and must be, capable of separation and distinction from other portions of the machine. The ruling of the master, that the profits arising from the improvement of the plain-, tiffs cannot be separated from the profits of the machine generally, seems to be based upon the idea that the improvement of the plaintiffs is all that is valuable in the machine. I cai.not but consider this a great mistake, as I have already shown.
I understand the rule to be settled, that, when the patent is for an improvement upon-a machine, the damages for the infringement of such patent are confined to the profits made by the use of the improvement only, and not by the manufacture of the whole instrument. What profit or advantage did the-defendants obtain by the use of the plain-: tiffs’ improvement? What advantage did they have that they would not have had, if they had built their machines without the improvement? In Philp v. Nock, 17 Wall. [84 U. S.] 460, although the case did not, perhaps, require an adjudication of the point, the rule is thus laid down, by Swayne, J.: “Where the infringement is confined to a party of the thing sold, the recovery must be, *882limited accordingly. It cannot be as if the entire thing were covered by the patent; or, where that is the case, as if the infringement were as large as the monopoly. * * * The plaintiff must show his damages by evidence. They must not be left to conjecture by the jury.” In Howry v. Whitney, 14 Wall. [81 U. S.] 620, 649, the precise point before us was in question. The defendant was charged by the master with $91,000, as the profits arising from the use of the plaintiff’s patent, in manufacturing car wheels, which was the profit obtained from the manufacture of the entire wheel. In delivering the opinion of the court, Strong, J,, says: “It is clear, that Whitney is not entitled to recover more than the profits actually made in consequence of the use of his process in the manufacture of the 19,819 wheels. It is the additional advantage the defendant derived from the process — advantage beyond what he had without it — for which he must account; * * * but the master charged the profit obtained from the entire wheel, instead of that resulting from the use of Whitney’s invention in a part of the manufacture. * * * It is a» true of a process invented as an improvement in a manufacture, as it is of an improvement in a machine, that an infringer is not liable to the extent of his entire profits in the manufacture. The question is, what advantage did the defendant derive from using the complainant’s invention, over what he had in using other processes then open to the public and adequate to enable him to obtain an equally beneficial result? The fruits of that advantage are his profits. They are all the benefits he derived from the existence of the Whitney invention.”
The burden of proof rested upon the complainants. The damages to the plaintiffs, or the profits to the defendants, (they are the same thing,) must be proved like the other points in the case. For all the profits or advantages with which they have been charged, (except that precise advantage derived from using the plaintiffs’ improvement,) the defendants may still be liable to other inventors, or they may have already paid for them to those inventors. Upon no principle can the plaintiffs assume that they belong to themselves, and call upon the defendants to disprove this assumption. It is not necessary further to examine the cases on this point The supreme court have decided it explicitly, and, if there are cases found to the contrary, they must be considered as overruled. The master should have decided that, as the plaintiffs had failed to show the profits or damages arising from the use of the improvement nominal damages only could be recovered.
The third exception is allowed, and, as it goes to the basis of the entire recovery, it is not necessary to consider the other exceptions in the case.
[See Case No. 5,643.]