Mr. Justice Lámar

delivered the opinion of the court. He stated the facts in the foregoing language, and continued:

The first and second assignments of error rest upon the same ground, and may be considered together. They are, first, that it was error for the court, upon the examination of the witness Chalmers, (who -was also one of the plaintiffs,) to admit in evidence the paper handed him showing an itemized statement of account aggregating $2531.78. It is contended tha,t evidence of this character, “ an unproved copy of an unproved account,” was inadmissible to show the alleged sale and delivery of merchandise; and, second, that the court erred in holding such inadmissible testimony to be sufficient evidence of an indebtedness to permit interest on it .to be recovered, as testified to. The assumption of fact involved in these assign-, ments, that the paper was admitted in. evidence, is not sufficiently supported by the .statement in the bill of exceptions.

*620 To obtain a reversal of a judgment it is necessary that the fact, upon which such reversal is claimed, should appear, from the record, sufficiently to be passed upon.

This bill of exceptions falls far short of a distinct statement that the paper was admitted in evidence; on the contrary, we think the import of the language is that it was not admitted, but that it wras handed to witness and read and used by him as a memorandum with which to refresh his recollection of the Articles mentioned in the account of plaintiffs. •'We do not think the court erred in allowing this to be done, and permitting his testimony to go to the jury for what-it was worth.

The third assignment of error is, that the court erred in refusing to allow thé witness Sabin, introduced in behalf of the defendant, to answer the question, “What was’the fair rental value per month of this mill and its attachments?”

This ruling of the court was manifestly proper. • It appears from the testimony of the witness himself that he knew .of no other silver mill in the neighborhood of Columbus; that he knew of none whatever at that time in operation; that he knew of no silver mill that had been rented in Leadville or in the State anywhere; and that this was the first silver mill he had ever been connected with, though he had been engaged in mining for twenty years, and was acquainted with gold mills enough to know what work they can perform and what they can earn. He evidently had no such knowledge of the marketable condition or rental value of such property as would fender his opinion of any use to the jury beyond the merest guess or conjecture. His knowledge and experience of mining mills was such as to render him competent to testify as to the cost of construction, the value of -machinery and the expense: of putting it up; and upon these points his testimony was admitted, and was to the effect, among other things, that the mill cost $75,000.

The fourth, fifth, sixth and seventh assignments of error are based upon the rulings of the court on the objections of the plaintiff to the other questions propounded by the defendant to the witnesses Sabin and Smith..

It does not appear clearly from the bill of exceptions for *621 what purpose these questions were propounded. Evidence to show.that the capacity of the mill was thirty tons a day had been offered and received to prove the rental value of the mill, arid perhaps very properly, as that might be a necessary preliminary fact leading up to the deteririination of its value for the rental. But after the defendant utterly failed to show, by any admissible evidence, that there was any rental value for a mill of that kind, we think the court did not err in holding that such rental value could be shown by proving the value or the amount of ore delivered and milled. If, however, the object of these questions (as counsel contends in his brief) was to prove the actual loss of use of the machinery during the period of stoppage, or the loss of the profits that, would have accrued but for the defective machinery,.the answers most favorable to defendant could only have tended to show losses too undefined to be subject to computation, and profits too remote and speculative to be capable of ascertainment. The ingenious argunient of counsel fails to convince us that the court erred in sustaining the plaintiffs’ objections to the questions.

The ninth assignment of error is, that - the court admitted the. evidence of the declarations of one Biotti, with regard to the placing of the .machinery of the mill, to ga to the jury.. The introduction of this evidence was objected to upon the ground that Biotti was not an agent of the defendant in respect to the matters covered by thesé alleged declarations.

The objection does',net seem to be valid. The witness testified that Biotti was authorized by defendant, in respect of the specifications in the contract between the parties, to give the draughtsman the incline of the hill, the room there was into the base of the retaining wall, the relative positions of where the furnace should be placed in position, and to give relative positions arid distances. The witness Chalmers, being recalled, testified that'** we were notified to comply with Biotti’s.directions. In looking over the original plan of the furnace the conveyors .were shown in the plan'. But Biotti said he preferred . . . desired us to follow the drawing in making the furnace. This drawing showed the conveyors, as after-wards put in the mill.”

*622 We-think this direction or declaration of Riotti was made with reference .to the very matters which, according to the testimony of Hurlbut and Chalmers, were directly within the scope of his authority and duty.

"We do not deem it necessary to consider the questions whether the instructions requested by the- defendant, as above set forth, and refused, are correct, as abstract propositions of law, with regard to the general principles governing the right of recoupment of damages. The bill "of exceptions does not show any evidence tending to prove all the facts which these instructions assume to exist. The counsel for plaintiff in error presses the* argument that the effect of the exclusion of the questions above mentioned shut out all evidence of the necessary and immediate ■ loss of profits during the time when, by reason of the -alleged breaches of the agreement, the use of the mill and machinery was lost to it. It would, in our opinion, have been "error to give instructions applicable to evidence not admitted. The legal principles in those instructions, - as requested, were, so far as they were founded, on the evidence, substantially put before the. jury in the general charge of the court.

The bill of exceptions states only so much of the charge as relates to the question of damages in the cause. The learned judge having, as we are authorized to assume, fairly left to the -jury the facts as to the alleged breaches of the contract, instructed them that, if they found the defendant entitled to deduct from the plaintiffs’ claim its damages resulting from the delay in the operations of the mill paused by the defective machinery, it was undoubtedly entitléd to deduct therefroip. the rental value of the mill. Recapitulating the evidence on this point, he then instructed the jury that, in the absence of all evidence as to the rental value, they were at liberty to allow interest on the investment; and that it was shown in evidence that the mill cost $75,000so that, if they found that the defendant was entitled to damages for delay .in running the mill, they would properly allow interest at ten per cent per- annum (which was the statutory rate in Colorado, Gen. Stat. Col. 1883, § 1706) for the ,time of the delay as *623 proven. He instructed them further, that there was more in the way of damages shown in the wages of the men employed in the mill whose time was lost while the mill was idle, and that for this loss of time, during which they were receiving wages from the defendant, the amount so paid could be ádded as an element of damages to be deducted from the plaintiffs’ demand.

We think the law of the case was fully disclosed to the jury, and that, fuller or more specific instructions were not required.

The judgment of the Circuit Court is

Affirmed,