And his testimony was supported by that of others who had seen the furnace in operation.

On the other hand, the plaintiffs, in rebuttal, called expert witnesses, who testified that the plaintiffs' furnace, as described in the patent, differed materially from that described by Karsten, and from the model of the one made by the defendant Grant, and who pointed out in their evidence the particulars in which that difference consisted, in the construction and arrangement of the furnace, in the principle of its operation, and in the results produced.

All of the evidence on both sides having been given, the whole of which is set out in the bill of exceptions, the court having refused to charge the jury as requested by the plaintiffs, instructed the jury to return a verdict for the defendants, which was done, and to this ruling exception was duly taken, and is now assigned for error.

Opinion of the Court.

The judgment entered on the verdict rendered in favor of the defendants, in pursuance of the direction of the court, can be maintained only on the ground, either that the legal identity of the furnace described by Karsten with that covered by the plaintiffs' patent was manifest as a matter of law, or that it was established as a matter of fact so conclusively by the evidence that a verdict the other way could not be supported, within the rule as stated in Randall v. Baltimore & Ohio Railroad Co., 109 U. S. 478.

Clearly it was not a matter of law that the specification of the plaintiffs' patent, and the publication of Karsten, taken in connection with the drawings intended in illustration, described the same thing. The differences were obvious, in the arrangement of the parts, and the relation of the basin in one, and the fore-hearth in the other, to the interior of the furnace, and the mode of connecting the one with the other, for the purpose of drawing the metal from the furnace. So that it certainly was not a matter of mere judicial knowledge, that these differences were either not material in any degree to the result, or, if material at all, were only such as would not require the exercise of the faculty of invention, but would be suggested by the skill of an experienced workman employed to produce the best result in the application of the well-known arrangements of the furnace. It was claimed, on behalf of the plaintiffs, that the furnace described in the patent and as used by them, embodied an idea not contained in or suggested by Karsten's publication. That idea consisted in the employment of a basin to receive the molten metal, located at a suitable elevation above the bottom of the furnace, and connected with the interior of the furnace by means of a tube, so that, instead of tapping a lead smelting furnace by withdrawing the molten metal through a tap-hole near the bottom, it was proposed to allow the metal to flow upward into the receiving basin under the operation of the familiar natural law that liquids will seek the same level in communicating vessels. The object to be attained by this arrangement was that clean metal, unaccompanied with slag or other impure products resulting from the operation of smelting lead ores, should, after settling to the bot

Syllabus.

tom of the furnace, by reason of its greater specific gravity, ascend through the connecting tube, as the mass of molten metal accumulates and rises within the furnace, into the receiving basin, and be dipped thence with a ladle. It was insisted by the patentees that no such arrangement and combination were to be found in Karsten's publication or in the furnaces depicted in his figures, and that the improvement which they constituted was not the result of mere mechanical skill, but sprang from a genuine effort of invention. And this view was supported by the opinion of many experts skilled in the art.

In our opinion this was a question of fact properly to be left for determination to the jury, under suitable instructions from the court upon the rules of law, which should guide them to their verdict. And there was evidence upon both sides of the issue sufficient to require that it should be weighed and considered by the jury in the determination of the question, and this implies that, if it had been submitted to the jury and the verdict had been for the plaintiffs, it would not have been the duty of the court to have it set aside as not supported by sufficient evidence. The court erred, we think, in withdrawing the case from the jury as it did by directing a verdict for the defendants. For this error the judgment is

Reversed and the cause is remanded, with directions to grant a new trial.

SOUTH BOSTON IRON COMPANY v. UNITED STATES.

APPEAL FROM THE COURT OF CLAIMS.

Argued April 8, 1886.-Decided April 19, 1886.

H offered to the Secretary of the Navy by letter to construct new boilers for certain vessels of the Navy. The offer was accepted at the Navy Department, by letter, and he was also thereby informed that the drawings and specifications would be furnished as soon as possible. A few days later he was notified to discontinue all work contracted for by him with the Depart

Statement of Facts.

ment. On a suit brought in the Court of Claims for damages for nonperformance of the contract, Held, that the letters did not constitute a contract with the United States under the provisions of Rev. Stat. § 3744-3749.

This was a suit in the Court of Claims to recover of the United States $75,000 damages, and $143,264.06 profits, which the claimant there alleged that it had suffered, or had been deprived of, by reason of the breach of two contracts which it claimed it had made for the construction of boilers for vessels belonging to the Navy of the United States. The defendants pleaded the general issue. The only proof of the alleged contract and of the breach and claim for damages was contained in the following correspondence:

"BOSTON, March 5th, 1877. WM. H. SHOCK, Chief of Bureau of Steam Engineering, Navy Department, Washington.

SIR Having learned that new boilers are required for the U. S. steamers Narragansett and Tuscarora, now at Mare Island Navy Yard, California, I submit the following proposition for the consideration of the Bureau of St. Engineering, viz. I will build such new boilers as may be required for the above-named ships, complete in all respects, from drawings and specifications furnished by the bureau, the material to be of the very best quality, and the workmanship to be first class in all respects; the boilers to be finished complete, ready for use, excepting erection on board the vessels, or in sections convenient for shipment, as the bureau may determine; the price of the same to be, if erected complete, ready for use, thirty and seven-eighths (303) cents per pound; if in sections, thirty and three-quarter (30) cents per pound; in either case to be delivered alongside of ship at New York or Boston, as may be determined by the bureau. I agree to receive in part payment such old material as may be at the disposal of the Department at the highest market prices.

I will also build one small boiler, complete in all respects, ready for use, for the tug-boat Snowdrop, now at Norfolk, from designs and specifications furnished by the bureau, and deliver at navy yard, Norfolk; material and workmanship

Statement of Facts.

to be of the best quality; price to be thirty and seven-eighths (303) cents per pound.

Very respectfully, your ob'd't serv't,

WILLIAM P. HUNT,

President South Boston Iron Co.

(Endorsement.)

"BUREAU OF STEAM ENGINEERING,

NAVY DEPARTMENT, March 7, 1877.

Received at the Navy Department, March 7, 1877.

Accepted by verbal directions of the Secretary of the Navy, in obedience to his order of this date.

W. H. SHOCK,

Ch'f of Bu. Stm Eng."

"NAVY DEPARTMENT,

BUREAU OF STEAM ENGINEERING,
WASHINGTON, March 7th, 1877.

SIR: By direction of the Hon. Secretary of the Navy, your offer of the 5th inst. for boilers for the Narragansett and Tuscarora is accepted, upon the terms and conditions named in said letter, the same to be delivered alongside vessel in New York harbor for shipment to Mare Island Navy Yard; also your offer for boilers for the tug Snowdrop, to be delivered in the Norfolk Navy Yard.

The specifications and drawings will be furnished as soon as prepared.

Respectfully,

WM. P. HUNT,

WM. H. SHOCK,
Chief of Bureau.

President South Boston Iron Co., Boston, Mass."

"BOSTON, March 3, 1877.

SIR: Having learned that new boilers are required for the iron-clad monitor Dictator, I submit the following proposition for the consideration of the Bureau of Steam Engineering, viz. I will build such new boiler as may be required for the above-named vessel complete in all respects from drawings