It was correctly ruled at the trial that interest upon the cost of the heating apparatus and its appliances, the expense of keeping them in good repair, and their depreciation in value, were not to be taken into account in the estimate of the expense of heating the building, towards’ which the defendant was bound to contribute. The lessor fits up ‘the building with such fixtures and conveniences as he thinks proper, and lets it in that condition to the various tenants. The interest upon the money invested, and the damage expected to be done to the building or any of its parts by use and general wear and decay, are matters for him to consider in determining upon the rent which he shall require of his tenants. The present lease does not in terms require of the defendant that he shall be charged with anything for repairs, depreciation and interest connected with the heating apparatus, and the natural and obvious interpretation of his covenant upon that subject is that he will contribute his proportion of the actual outlay or expenditure incurred in the current, ordinary and regular supply and management of that apparatus for the general benefit of the tenants.
Upon the question as to the damages suffered by the defendant by reason of the failure of the apparatus to keep his premises properly heated, the ordinary course of proof would have been for him to show that some inconvenience or injury produced by that cause had had the effect to increase his expenses or to diminish his receipts. He was permitted to show the average daily expenses of his business under ordinary circumstances, not for the purpose of showing that there had been an increase of expense from the cause complained of, but in the language of the bill of exceptions, “ to prove said damages.” But it is obvious that the damages resulting from the accident complained of do not depend upon, and are not affected by, the ordinary expenses *58incident to the prosecution of his business. The only mode, in which the evidence as to those expenses could throw any light upon the question of damages, would be fyy comparing the ex penses of different periods of time with each other, but it does not appear to have been used for any such purpose. It had no tendency whatever to prove the damages, and was incompetent and inadmissible for the purpose for which it was admitted by the court. It is, therefore, a case of incompetent evidence, introducing into the computation of damages an element that does not belong to it, and capable of operating injuriously to the plaintiff’s rights. Upon this point, therefore, the plaintiff’s
Exceptions are sustained.