Opinion by

This is an action of assumpsit to recover damages for the breach of a contract. A number of the assignments of error relate to the legality of the contract and are predicated upon the theory that appellant company undertook to do what it could not do without the consent of the municipality and adjoining property owner, and if such consent could not be obtained, the undertaking was illegal and the contract void. On this question we agree with the conclusion reached by the learned trial judge and with the views expressed by counsel for appellees. There is nothing on the face of the contract to indicate an illegal purpose. The mere fact that it involved a change of grade in an old road over which the public had an easement did not make the purpose unlawful and the contract void ab initio. It only required the consent of the city and the adjoining prop*112erty owner to do everything the contracting party agreed to dp. The presumption is that such consent had been obtained or could be secured, and in either event the contract would be perfectly valid. If appellant did not or could not secure such consent, the facts relied on should have been set out in the affidavit of defense. The general averment that the contract had been performed so far as it was lawful is not sufficient under the pleadings and rules of court, and the testimony offered relating to this question was properly excluded.

As to the measure of damages, our view is different. The learned court below directed a verdict for plaintiffs for the full amount claimed in the declaration, together with accrued interest thereon. The amount was determined by multiplying the number of cubic yards necessary to complete the fill as set out in the statement of claim, by the estimated cost per cubic yard averred in the declaration. In other words, the measure of damages was held to be the cost of completion. It was further held that if appellant desired to controvert the fact as to the number of cubic yards alleged to be necessary to complete the fill or the cost thereof, these matters should have been set up in the affidavit of defense. With this position we do not agree. The affidavit of defense denies that appellant ever covenanted to fill plaintiff’s property with 150,000 cubic yards of earth or to place any specific amount of waste material upon the same. Since the alleged amount of earth required to complete the fill is arrived at in the statement of claim by deducting from the estimated number of cubic yards required to make it, the number of cubic yards already deposited, it would seem like sticking in the bark to say that appellant should be denied the right to raise the question of its liability to furnish the whole number of cubic yards or some fractional part thereof because it had failed to specifically deny its obligation to furnish 71,628 cubic yards which it was alleged were necessary to complete the contract. The denial of appellant’s liability to furnish the greater amount necessarily includes the Jesser and certainly is sufficient to put upon plaintiffs the burden of establishing not only the contract and the liability of appellant under it, but the damages suffered by reason of the *113alleged breach. Again, in the affidavit of defense it is denied that the appellant is indebted to the plaintiffs in the sum of $35,814, being the amount claimed in the statement of claim, or any other sum whatever. Certainly, these denials are sufficient to put plaintiffs upon notice that the liability of appellant under the contract would be contested and if its liability be established, the measure of damages which is a conclusion of law, could not properly be determined until the evidence was in and the facts understood. This is the doctrine of Seely v. Alden, 61 Pa. 302, and numerous other cases. Independently, however, of the question whether it was necessary to include in the affidavit of defense a denial of the measure of damages inferentially set up in the statement of claim, the general rule is that the plaintiffs must prove the amount of damages sustained by them or they will only be entitled to nominal damages and that failure to deny the amount of damages alleged to have been sustained does not admit them: Lucot v. Rodgers, 159 Pa. 58; Howell v. Bennett, 81 N. Y. Sup. Ct. 555. It has been well said that it is difficult to point out in advance what the true measure of damages should be under a given state of facts. If there be different modes of measuring damages, depending on the circumstances, the court should first hear the evidence and instruct the jury afterward as to the proper measure to be applied. The underlying principle in such cases is that the damages must be such as might naturally be expected to follow a breach of the contract, keeping in mind the benefit which the contracting parties had in contemplation when the agreement was entered into. As we read the contract in the present case there was no binding covenant requiring appellant to furnish 150,000 cubic yards of earth to plaintiffs. There was a license or privilege granted to deposit on the lands of plaintiffs so much earth, estimated at 150,000 cubic yards, as would be necessary to make the grade of the road as agreed upon. The railroad company was desirous of securing a place to dump its waste material, and the appellees had such a property. These were the conditions when the contract was made. The appellees have a right to the benefit of their bargain, but nothing more. Under the facts of this case *114the true measure of damages would seem to be the' difference in the value of the plaintiffs’ lands with the fill completed and as it was at the time of the breach with the fill only partially made. In this respect what was said in Seely v. Alden, 61 Pa. 302, applies: “It may turn out that the cost of removing the deposit in a certain case would be less than the difference in the value of the land, and then the cost of removal would be the proper measure of damages; or it may be that the cost of removal would be much greater than the injury by the deposit when the true measure would be the difference in value merely.” The question of the proper measure of damages must always be taken .into consideration by the court in the proper disposition of any case wherein damages are claimed: Wilkinson v. North East Borough, 215 Pa. 486. For the reason, therefore, that the proper measure of damages was not adopted in the present case the judgment is reversed and a venire facias de novo awarded.