delivered the opinion of this> court.
On the 23rd of February 1852, the appellants leased to the appellees, by an agreement under seal, a stone mill, then but recently rebuilt, after having been burnt some time previously. That portion of the agreement which relates particularly to-the present controversy, is in the following language: “And-
the said Joseph and Samuel further promise and agree to keep the mill greased and oiled, and as to all what belongs to and is to be done by the miller, to do and perform, and keep in-repair the said mill, and to deliver up all the said premises hereinbefore leased, at the expiration of their tenancy,, in as good order and repair as they find them, natural wear and tear and fire excepted.”
During the term the mill fell down, and not being repaired or rebuilt, after the termination of the lease, the present suit *336was instituted, to recover damages' for what the appellants charge to be a breach of the covenant, to repair and deliver up the property in good order.
The plaintiffs contend, that under the contract the defendants were bound to return the mill in as good order and repair as they found it, and also that the falling down of the same did not come within the exception of natural wear and tear. But the defendants insist that the mill fell in consequence of a defect, unknown to them, in the main cross wall, resulting from the action of the fire upon the lime-stone, of which it was composed, whilst they were using the mill with reasonable and proper care, and therefore they are excused from repairing or rebuilding, by virtue of the exception contained in the lease.
The plaintiffs offered proof for the purpose of showing the nature and condition of the mill, and especially of the main cross wall; that the defendants had in the mill a much larger quantity of wheat than was prudent or proper; and that the weight of the wheat occasioned the injury. The defendants, however, examined witnesses to show the defective character of the wall; that from the size and general appearance of the mill, any intelligent miller would have supposed the mill-house capable of bearing a much larger quantity of wheat than it contained when it fell and that the condition of the wall, after the accident, showed the injury to have been occasioned by the defect in the wall. Whether the proof establishes the correctness of the plaintiffs’ theory, or that of the defendants’,, we are not the tribunal to decide. That was for the jury.. So far as we have any duty to perform, it is only necessary for us to know .that such proof was offered.
Before we consider the prayers, it is proper to enquire whether, by the exception in the agreement, the defendants are exonerated from rebuilding the mill if it fell in consequence of its own defective construction, and not from an- improper use of it by the defendants?
Under a covenant to pay rent, the tenant is bound to pay, even where the premises are destroyed by fire, flood, tempest, *337lightning, or the violence of a mob, unless the lease contains an express clause of exoneration on account of such injuries. The reason given for the rule is, because the party may, if he thinks proper, provide against such casualties by express contract. The principle rests upon the distinction between a duty imposed by law, and one voluntarily assumed by the party himself. In the former he may be excused from the duty, if he is disabled from performing it without fault on his part; whilst in the latter he is bound to make it good, notwithstanding any accident by inevitable necessity. 2 Platt on Leases, 120, and 12 Mees, & Wels., 86, 87, 88, Hart vs. Windsor. In the last case it is said, “ There is no implied warranty on a lease of a house, or of land, that it is or shall be reasonably fit for habitation or cultivation. The implied contract relates only to the estate, not to the condition of the property.”
The appellants say these principles apply not only to covenants for payment of rent, but also to covenants for repairs. Admitting this to be true in reference to a contract to repair generally, and to return the property in good order, without any express exception or qualification, still the question arises, whether, under the exception, in the present case, in regard to natural wear and tear, the defendants are not excused from rebuilding the mill, provided the injury was not occasioned by any improper use of it by them ?
Although when a lease contains no express contract of warranty that the property is or shall be fit for the purpose for which it may be rented, there is no implied warranty to that effect, and in case the property falls down in consequence of some inherent defect, the lessor is not bound to repair, and yet the lessee will be compelled to pay the rent; nevertheless the lessee will not be bound to repair in such a case, if there be a covenant to repair and to return the property in the same condition he received it, natural wear and tear excepted; provided that at the time of the loss the lessee was using the property in a reasonable and suitable manner, according to the object and design of the parties when the contract was made. If a man rents a house for a particular purpose, and *338•that is known to both parties, the lessee surely has the right ■to usé it for such purpose, provided he does so with a reasonable degree of prudence and care. And if, during such use, the house tumbles down, in consequence of some defect in its structure, does not the loss result from natural wear and tear? The defect is a part of the nature of the building, and if that ’nature is the cause of the mischief, the loss is necessarily the consequence of natural wear and tear.
The plaintiffs submitted four prayers. The first, second ,and fourth the court rejected, but granted the third, with a qualification.
The first and second were properly refused. They were defective in consequence of assuming it to be necessary for the defendants to satisfy the jury that the plaintiffs, or one of them, knew of the alleged secret defect or unsoundness in the wall, and concealed the same from the defendants.
. If, irrespective of the defect in the wall, the defendants were making such use of the mill as a man of ordinary care and prudence would have made, and the defendants were ignorant of the defect, and it was of such a secret or concealed character that it was not to be discovered by reasonable and .ordinary diligence, then, for the purposes of the defence, there was no necessity to prove that the plaintiffs, or either of them, had a knowledge of the defect, and concealed it from the defendants.
These prayers do not refer to the pleadings in express terms, .and if they could be considered as calling our attention to. them, still the error we have noticed would not be cured. The second plea does not rely upon the plaintiffs’ knowledge .of the' unsound condition of the wall, and the concealment of it. The third plea does. Assuming that the prayers have reference to the pleadings, there is certainly nothing which confines or points them to the issue joined upon the third plea. And the second plea presenting no issue upon this particular subject, which, in our opinion, is, in itself, of no importance to. the defence, the prayers must be considered erroneous.
We see no evidence to show that the defendants had a *339knowledge of the unsound condition of the wall. Proof of that description might have exerted a very important influence in the cause.
The fourth prayer is: “ That by the true construction of the covenant declared on in this cause, and the exception therein contained as to the natural wear and tear of the mill, the same means and extends only to such natural wear and tear, as are produced in the reasonable and careful use of the said mill, and not to any accidental or sudden cause, at once throwing down and prostrating the same.” The prayer is vicious, because it asserts the proposition, that no accidental or sudden throwing down and prostration of the mill could be natural wear or tear, no matter how reasonably and carefully the mill might have been used. The error consists in supposing the exception can include no injury which is not gradual and the work of time; or in other words, the exception is considered as synonymous with gradual decay. If the word wear may seem to sanction such a construction, surely the same cannot be said of tear. Suppose a mill just erected and rented, under such a lease as the present. In the machinery there is a concealed or undiscovered radical defect. The tenant enters upon the premises, and in a very short time after the mill is put in operation the defect causes so serious an injury to the machinery, as to render the mill useless, unless reconstructed or repaired at very great expense^ can it be possible that the lessee would be bound to make good the loss, although his lease provided for his exoneration from repairing injuries arising from natural wear and tear? If in consequence of the nature of the mill, and not from any improper use of it, the injury occurred, although suddenly, would it not be the result of natural wear and tear?
The third prayer is: “That if the jury shall find from the evidence in the cause that the said defendants entered upon the said demised premises, in pursuance of the said agreement declared on, and which is in evidence in this cause, and used and enjoyed the same, and that during the said term or tenancy, and while the said defendants were so in possession, *340the said mill-house fell down and was prostrated, and became ruinous, and that such falling down, prostration and ruination, were not produced by natural wear and tear in the reasonable and careful use of the said mill, nor by fire, and that the said defendants surrendered up and left the said mill and premises, at the expiration of their said term or tenancy as aforesaid, in such ruined and prostrated condition without repairing and rebuilding the said mill, then the plaintiffs are entitled to recover in this action, unless the jury shall further find from the said evidence that there were existing at the time of the making of the said agreement, undiscoverable defects in the main or partition wall mentioned in the said defendants’ pleas, and that such latent and undiscoverable defects in the said wall were the immediate and direct cause of the falling down and prostration of the said mill without any manner of default, carelessness, negligence or mismanagement of the said mill by the said defendants, their agents or servants; and shall further find that the said defendants could not, nor did either of them, at the time of the making of the said agreement, or at any time before the said falling down and prostration as aforesaid of the said mill, know of or have any knowledge whatever of such defects in the said wall.”
From the bill of exceptions it appears the court granted the third prayer, “with this qualification or exception, to wit, that if the jury should find that said secret defects were unknown to the said defendants, and were undiscoverable or could not be known by reasonable and ordinary diligence.” We see no error in the qualification. It relates to the concluding portion of the prayer, the language of which was well calculated to mislead the jury. In most explicit terms it required the proof in defence to satisfy the jury, not only that neither of the defendants, at the time of making the contract, or at any time before the mill fell down, knew of, or had any knowledge whatever of, the defects in the wall, but that the defendants could not have any such knowledge. With such a prayer before them the jury might very well have believed they were not authorized to excuse the defendants from lia*341bility, on account of defects in the wall, unless they were convinced that it was impossible for the defendants to have acquired a knowledge of those defects, the prayer expressly requiring them to find that the defendants could not know, or have any knowledge of, the defects. The qualification presents the matter correctly, by presenting to the jury the enquiry, whether the defects were unknown to the defendants, and also whether they were undiscoverable, or could not be known by reasonable and ordinary diligence.
Immediately following this qualification of the third prayer the bill of exceptions proceeds thus: “And the said court w*as further of the opinion, and so instructed the jury, that if they shall believe from the evidence that the injury was occasioned from the reasonable and proper use of the said mill by the defendants, their agents and servants, and without any neglect or default of the said defendants, then the plaintiffs are not entitled to recover.
But if they shall believe from the evidence the injury was occasioned from the want of proper care, or from neglect or unreasonable use of said mill, then the plaintiffs will be entitled to recover in this action.”
This further opinion and instruction, which seems to have been given in connection with the third prayer, and the qualification of the same, we understand as having been designed by the court as a reiteration, in language somewhat different, of the same subject of inquiry submitted by the prayer; that is, whether the falling of the mill resulted from the defect in itself whilst being used by the defendants, their agents and servants, with reasonable and proper care, and without any neglect or default on their part, or was occasioned by want of proper care, or from neglect or unreasonable use of the milk
Objection has been made to this further instruction of the court, because it submits to the jury a question of law and not of fact, by authorizing them to decide upon what constituted reasonable and proper use of the mill. Admitting this to be true, still the plaintiffs cannot complain of it, for it is perfectly consistent with their third prayer, which submits to *342the jury to find whether the falling of the mill was or was not produced, by natural wear and tear, in the reasonable and careful use thereof. Moreover, it will be seen the second plea asserts, that the falling down of the mill was without the default of the defendants, or either of them, or any of their agents or servants, and was the result of natural wear and tear, in the reasonable use of the mill by the defendants. Upon this plea issue was joined. In this state of pleading, with the plaintiffs’ third prayer before the court, and in the absence of any prayer asking an instruction to define what constituted reasonable use. the instruction given by the court could not be erroneous. When considering an objection to a prayer because it submitted to the jury a question of law, Judge Dorsey said, in delivering the opinion of the court: “It surely could not have been error in the court in submitting, as they did, the issue in fact to the jury in the very terms in which it had been joined.” Planters Bank of Prince George's County vs. Bank of Alexandria, 10 G. & J., 353.
Judgment affirmed. ’