This writ of error is brought to review the judgment upon a second trial of an action at law for damages for the infringement of letters patent No. 172,608, of date January 27, 1876, issued to John W. Cassiday, for improvements in drying apparatus. The improvements covered by the patent refer to that class of fruit driers known as "stack driers,” and are embraced in two claims, — the first, for a system of fines for distributing hot air through the stack of trays at different points; the second, for a mechanism to raise the fruit trays vertically, so that a tray may be inserted at the bottom of the stack, and be gradually raised in the process of drying, and finally re moved from the top. Only the second claim was shown to have been infringed. At the first trial, the patentee, in endeavoring to establish the measure of damages by proof of an established royalty. furnished proof that the royalty which had been received was for the entire machine, including both the claims of the patent, and did not attempt to segregate the amount due to each claim. *586 Upon writ of error to this court the judgment was reversed (Packing Co. v. Cassiday, 58 Fed. 257 , 3 C. C. A. 525 ), the court holding that “the proof of a license fee for two improvements in fruit driers is not competent in order to show the damages sustained by an infringement of one of these improvements.”

Upon the second trial it is assigned that the court erred, first, in refusing to charge the jury to find nominal damages only. This instruction was asked upon the theory that the evidence in the second trial, as upon the first, failed to apportion the amount of the royalty received by the patentee to the respective claims covered by the patent. This contention is not sustained by the bill of exceptions. It there appears that upon the second trial there was evidence tending to show that the royalty which the patentee had received was for the second claim of his patent alone, and that the improvement covered by the first claim was not only valueless, but was a detriment to the machine. Under such testimony the jury could properly apportion all the damages to the second claim, and it would have been error to charge as requested by the plaintiff in error.

It is further assigned as error that the court instructed the jury as follows:

It is urged that these instructions are erroneous, for the reason that they permit the jury to determine what was a reasonable royalty for the plaintiff’s invention, and to fix the damages at that sum. The law upon this subject, as stated in Walker on Patents (section 563) is as follows:

The rule so announced is admitted by the plaintiff in error to be a correct statement of the law if there be added thereto the single qualification that there must be testimony in the case tending to show what would have been a reasonable royalty, and it is denied that any such evidence was offered in this case. The admis *587 Sion, in shori, concedes tlie correciuess of the charge as an exposition of the law, but challenges its correctness as applied to the fads disclosed oil the trial. On referring to the bill of exceptions, it will be seen that the patentee icslifiod that he had endeavored to .fix the royalty at $100; that he had in some instances collected that amount as royalty; Unit he had sold his driers at $250, and that they had cost him S!)2; that his profits were -Si58, of which lie estimated $58 to be the profits oí die nupatented portions, leaving $100 as profit on the invention which was «lid to be infringed. He further testified that, in his judgment, that sum was a, fair and reasonable royally. There was evidence that the established royalty on the prior machine of Aiden, a much more expensive drier, made* nnder a patent containing chums similar to those of the plaintiffs patent, was $1,000, while its cost was but $250; and íhav the lifting device in the Aiden patent', was made at an expense of $75, while that, of: the patent in controversy cost bur, $17. If: is difficult to conceive how there could have been more direct proof concerning the amount of a reasonable royalty in a ease such as this. The estimate of the patentee placing it at $100 is, it is true, an expression of his opinion; but it is an opinion based to some extent upon figures and estimates. He evidently disclosed all the information he possessed upon (he subject, — the cost of manu facture, the Sidling price, so far as he had sold, the profit, and Ms estimate of the proportion of the profit that should be attributable io the infringed invention, in this class of patents there are necessarily no data from which the value of a royalty can be calculated wish mathematical certainty. The damages itere, like damages in many oilier classes of cases, are calculable upon such evidence as it is in the nature of the case possible to produce.

The plaintiff was clearly entitled to damages for the infringement. If there had been an established royalty, the jury could have taken that sum as the measure of damages. In the absence of such royalty, and in the absence of proof of lost sales or injury by competition, the only measure of damages was such sum as' under all the dmimstaiic.es, would have been a reasonable royalty for the defendant to have paid. This amount it was the province of the jury to determine. In so doing, they did not make a contract for the parties, but found a measure of damages. McKeever v. U. S., 14 Ct. Cl. 414 ; Ross v. Railway Co., 45 Fed. 424 : Royer v. Coupe, 29 Fed. 371 ; Cary v. Manufacturing Co., 37 Fed. 654 .

We find no error, and the judgment of the court below is affirmed, with costs to the defendant in error.