delivered the opinion of the court.
We are prevented from considering many important and interesting questions, which might have been presented upon ■the evidence and pleadings in this cause, because they were not raised in the court below, as required by the act of 1825, chap. 117. Under that act, to authorise the Court of Appeals to review a judgment of the county court, it must appear by the hills of exceptions, that the point or question upon which •the reversal or affirmance of the judgment is sought, was .presented substantially to the county court, and that the decision was made tipon such point or question. In the case now before us, there were three exceptions taken to the ruling of the court below, and we shall proceed only to the consideration of the questions in their order, which arise out of •those exceptions.
The first question raised in the first bill of exceptions, was as to the admissibility of the evidence of Stam, which related to the want of repairs to the tail-race. The appellant, in her lease to the plaintiff, (appellee,) had covenanted “to keep the mill in good repairs,and under this general covenant, the appellee sought to make her answerable in damages for neglecting to keep the tail-race in good repair. If we were to confine ourselves strictly to the precise point raised, and the manner in which it is presented, we would clearly be obliged to pronounce the decision of the county court erroneous, but for a different reason than the one assigned for the decision. This court must consider what particular point or question the county court has decided, and determine accordingly, whether it is correct or erroneous; and not whether the reasons assigned by the counsel or court, on the record, authorises what has *338been done; and, therefore, where the admissibility of the evidence offered, as in this case, being objected to, it is wholly immaterial whether it was admissible or not for the special reasons assigned, but this court will consider the distinct question, whether it was or was not competent testimony. 3 Gill and John., 435
In the language of the first exception, “the plaintiff offered to prove by Daniel Stam, that the tail-race to the mill was not kept in good order and repair, which lessened the power of said mill, and impaired its usefulness.” Nothing is said about the time when the mill-race was thus out of repair. It may have been conceded that the race was out of repair, but denied that it was out of repair during the time of the plaintiff’s lease, or during the time alleged in his declaration that he sustained injury, by reason of the omission to repair on the part of the defendant. For this reason, we think the testimony ought to have been rejected, while we might concede that the obligation to repair the race was embraced in the general covenant to keep the mill in good repairs, and that evidence might have been offered to show that those repairs were not made as alleged in the declaration.
The inference however is irresistible, that although no time is fixed by the witness in his testimony, as set out in the first exception, in regard to the want of repairs in the race, yet the testimony which formed the subject of this exception, and to which the mind of the court below was evidently directed, was the same which is fully set forth in the second exception. Though more explicit as to time, yet the witness still failed to bring the want of repairs complained of, within the time alleged in the declaration of the plaintiff, in which the defendant is charged with having suffered the mill and race to be in bad repairs. In order to make testimony legally admissible, it must correspond with the allegations contained in the declaration, and be confined to the issue. In the books a distinction is made between allegations of matter of substance, and allegations of matter of essential description. The former may be substantially proved; but the latter must be proved *339with a degree of strictness, extending, in some cases, even to literal precision. Every allegation, essential to the issue must be proved, in whatever form it be stated. There is however a class of circumstances, not essential in their nature, such as time for example, but which may become so by being inseparably connected with the essential allegation. These must be proved as laid, unless they are stated under a videlicet, the office of which is to mark, that the party does not undertake to prove the precise circumstances alleged; and in such cases he is not holden to prove them. 1 Greenleaf on Ev. sec. 60. In the case now before us, the plaintiff in his declaration positively alleges without any qualifications, and unaccompanied with a videlicet, that “on the contrary, the said defendant, suffered and permitted the said mill and the said mill-race to continue so ruinous, and in bad repair, from the first day of April 1847, until the expiration of the said term of two years.” We think the plaintiff should be confined in his proof, under this averment, to the time when he alleges that the mill was in badrepairs. Arch. Land and Ten., 178, (53 Law Lib., 173.) We have examined the testimony of Siam attentively, and find that no part of it fixes the omission of the defendant, to repair the mill-race within the time laid in the declaration, which was subsequent to the 1st April 1847. He speaks positively of its being out of repair during the lease, but non constat, it might have been out of repair prior to the 1st April 1847, a period in which the plaintiff makes no complaint in his declaration, and which if he had, the defendant might successfully have refuted.
While we are willing to concede, that the general covenant “to keep the mill in good repair,” would embrace the obligation to keep also the tail-race in repair, yet we are not willing by any such construction of the contract, to shift the legal and usual responsibilities which belong to the miller over to the landlord. By keeping the mill in repair, is not meant the ordinary attention and care which is usually required of millers in operating mills, and which indeed constitute a part of their trade; such as, for instance, cleaning and *340dressing the stones, adjusting and regulating the general machinery of the mill, cleaning the race of such deposits or accretions as would follow the ordinary use of the mill, and such other similar acts which demand the miller’s skill, yet which require neither the expenditure of money, nor the consumption of much time or labor. Under the covenant to repair generally, the covenantor will be bound to keep the building in as good a state, as it was when the agreement was made, to make good all deteriorations arising from natural decay, and all injuries resulting from inevitable accident, but he is not bound to do more. And where an old house is rented, with the usual covenants to keep the same in repair, the covenantor will not be bound to put it in an improved state, nor to avert the consequences of the' elements, but only to keep it in a state in which it was at the time of the demise, by the timely expenditure of money and care. Guttridge vs. Munyard, 7 C. & P., 129. Archbold's Law of Landlord and Tenant, 176. (53 Law Lib., 173.)
The court, therefore, should have confined the testimony of the plaintiff to such repairs, as were clearly the duty of the landlord to have made, which we think has not been done in this case. For the reasons stated, we reverse the court below, on the first exception.
As respects the testimony of Samuel Middlekauff, embraced in the second exception, we are of opinion that the county court was right in rejecting it. While it is not in the power of any person, to force another to render him offices of friendship or service, yet if these offices are voluntarily or even gratuitously assumed, the party is bound to act in conformity with the terms of the undertaking, and faithfully to discharge the duties thus assumed. An agent of this kind is responsible to his principal for the consequences of his negligence. Coggs vs. Bernard, 2 Raym., 909. Walker vs. Smith, 1 Wash. C. C. Rep., 152.
Being thus the agent of the defendant, and liable to her for any damages which might result to her from a neglect of his duty, Middlekauff is, therefore, clearly interested in the result *341of this suit, and not a competent witness without a release. The principle is thus substantially stated in the books.
In an action against the principal for damages, occasioned by the neglect of his agent, the latter is not a competent witness for the defendant, without a release; for he isa as a gene ral rule, liable to his employer, in a subsequent action, to refund the amount of damages which the latter may have paid; and though the record will not he evidence against the agent, to establish the fact of misconduct, yet it will always be admissible to show the amount of damages recovered against his employer. Hamilton vs. Cutts, 4 Mass., 349, Tyler vs. Ulmer, 12 Mass., 163. Miller vs. Falconer, 1 Camp., 251.
It must he admitted that the question arising upon the third exception, or upon the defendant’s prayer, is one which is attended with very considerable difficulty. To adopt any general rule in relation to the measure of damages, which would apply to, and govern every case which might arise, involving that question, is a matter almost of impossibility. The defendant, in her prayer, asks the court to limit the measure of damages, to the costs and expense to which the plaintiff would have been subjected, for the purpose of properly repairing the mill and race; the injury resulting from the neglect to make said repairs, being the ground of the plaintiff’s action. The court, we think, were right in refusing this prayer. To have granted it, would have had the effect of confining the plaintiff’s damages within limits too narrow. On the other hand, we think, that while the court properly rejected this prayer, it could, with propriety, nevertheless, have prescribed some limits beyond which the plaintiff should not go in the introduction of testimony to swell his damages, and should have adopted some rule as a guide to the jury in the amount of damages to he awarded in the case. The general rule of damages in cases like the one now before us, as laid down by Mr. W. W. Story, in his work on contracts, sec. 1022, is this: “The consequential injury, fairly and naturally resulting to the plaintiff from the breach, will be ground for additional compensation. E^ut merely speculative injuries, founded on un*342certain_future contingencies, afford no ground for damages.” And in Loker vs. Damon, 17 Pick., 288, Shaw, C. J., lays down the same rule, but in distincter and more precise terms. “In assessing damages,” he says, “the direct and immediate consequences of the injurious act are to be regarded, and not remote, speculative and contingent consequences, which the party injured might easily have avoided by his own act.” The rule is still further narrowed down, and made more directly to apply to the case we are considering, in Archbold’s Law of Land. and Ten., 177, (53 Law Lib., 174,) and Story on Contracts, sec. 930. The substance of these two authorities, is, that the mode of proving the damages sustained by the breach of a covenant to repair, is, by showing by competent persons, the sum it would take to put the premises into that state of repair in which the defendant ought to have kept them under the covenant, and the jury in such cases may allow, not only the actual expense of the repairs, but also some compensation for the loss of the use of the premises, whilst they were undergoing repairs. In the case of Blanchard vs. Ely and others, 21 Wend., 342, the court decide, that in an action for the recovery of the price stipulated for the building of a steamboat, the plaintiff is entitled to recover the full amount, without deduction by way of recoupment of damages to the defendant, in consequence of injury sustained by him for the loss of trips, and the profits resulting therefrom, occasioned by defects in the boat, or its machinery; but that the defendant is only entitled to an allowance for moneys necessarily expended by him in supplying defects in the vessel, so as to make it conform to the plan specified in the contract. So, in the same case, where a number of authorities are cited, in illustration of the principle decided, the court lay down this general rule, that a lessee who is evicted by a title paramount to that of his lessor, may claim the expense of removal and indemnity for advanced rents, but is not entitled to recover for loss of custom established while residing in the house.
It remains for the court to apply these general principles, *343to the case now before us. Whether the injuries complained of, by the plaintiff, are such “which he might easily have of the repairs, which were required, and the ability of the avoided by his own act,” will depend entirely upon the nature plaintiff' to have made them. If the needed repairs were such as might have been made without the expenditure of money, and with little care and labor, then clearly, the plaintiff not having made them would have been liable to the imputation of having invited or permitted the injuries, of which he complains, and could not recover damages for the same. So, if the plaintiff placed his wheat, where he knew at the time, it would be injured by the drippings from a leak in the roof, he is not entitled to recover for the injury he may sustain thereby ; for such conduct would have amounted to gross negligence, and he alone should suffer for his folly. Further, if the jury should find that the plaintiff, was able without inconvenience to have repaired the race, which the witness thinks could have been done with twenty dollars worth of labor, it would have been equivalent to “gross negligence,” (the language used in Loker vs. Damon,) for him to have omitted doing so, and thereby involved himself in a loss of ten dollars daily, as estimated by the witness.
We do not however mean to intimate, that under all circumstances-the lessee in this case was first bound to repair at his own cost. Many repairs may have been needed which his peculiar situation or circumstances would not have permitted him to have made, and thus one of the very purposes he may have had in view in requiring from his landlord a covenant to repair, might have been defeated. In such a case it could not be said that the tenant permitted, “or could have avoided,” the injuries of which he complains, because it was not in his power to have prevented them.
Under this covenant, clearly, the tenant would be entitled to be remunerated for all expenditures of money, time and labor made in repairing the mill, also compensation for the loss of the use of the premises, whilst they were being placed in the condition in which the landlord should have kept them; *344and for all direct and immediate damages resulting from the neglect of the lessor to make such repairs, and which it was not in the power of the tenant easily to have avoided. Upon the authority of Story on contracts, and the case of Blanchard and Ely, 21 Wend., (and numerous other cases we might cite,) we think the loss of custom complained of by the plaintiff, and proved by the witnesses, was too speculative, and depended upon too many and remote contingencies, to constitute a proper ground for damages in this case.
We think complete justice cannot be done without the cause being submitted to another jury. The plain inference is, that the jury who determined this case, were permitted to consider matters which ought not to have entered into their verdict, and have allowed damages under the evidence submitted to them, which exceed those which the law and justice of the case would warrant. We therefore reverse the judgment and remand the cause.
Judgment reversed and procedendo awarded,