delivered the opinion of the Court:

This was an action of assumpsit, founded on an alleged breach of contract to deliver to appellee sixty head of good cattle, out of a lot of eighty head, then owned by 'appellant, which appellee had purchased of'appellant; and which he agreed to deliver to him on any day between the first and fifteenth days of March, 1865, at the option of appellee at Camp Point. And appellee was to pay appellant therefor, at the rate of six dollars per hundred pounds gross weight, on delivery. And that on the 13th day of March, 1865, appellee notified appellant that he was ready to receive the cattle at Camp Point, and offered to pay for the same at the price agreed upon by the parties; but appellant failed and neglected so to do. The second count is, substantially, the same as the first. The third count, after stating the contract as in the first, avers that after making the contract and before the time of delivery, and on the 20th day of February, 1865, appellant sold and delivered the cattle to Farlow, and put it out of his power to deliver the cattle to appellee.

The fourth count states the contract generally, of the sale of the cattle, and that they were to be delivered between the first and fifteenth of March, and a sale and delivery by appellant to Farlow, before the 1st of March, and thereby put it out of his power to deliver the cattle to appellee, and that Farlow was an innocent purchaser. The plea of the general issue was filed, and a trial had, resulting in a verdict and judgment against appellant; to reverse which he prosecutes this appeal.

It is urged that the contract is indefinite and uncertain, as no definite quantity is averred. The various counts aver the agreement to sell sixty head of cattle, to he selected from a lot of eighty. This we think is sufficiently definite, as the evidence does not show that any number of pounds was sold. The declaration is always sufficiently definite and certain when it states the contract in terms or in substance. If there was no agreement for a specific number of pounds, it would have been a variance to have so stated the agreement. The contract was lawful, and was stated as proved by the evidence, and no objection is perceived to it, and it was sufficient to warrant a recovery if proved.

• It is insisted that there was no demand on appellant to deliver the cattle, and hence appellee did not exercise an option. A witness states that by the authority and under appellee’s direction, he went to see appellant, and found a man at his house who said his name was Thomas White. That he informed him that he had come for the cattle he had sold appellee; he replied that he had sold appellee no cattle. This was a question for the jury to determine whether the demand was made of appellant or of some other person. They have found that it was of appellee, and wé think that the evidence warranted the finding, and also that there was a demand.

It is urged that the evidence as to what the cattle might have been made to weigh was improper, as it did not afford the proper measure of damages. It is true that such evidence is not as satisfactory as would have been evidence of what the cattle did weigh. But appellant, by selling the cattle to Far-low, seems to have put it out of the power of appellee to prove what they weighed. And if the estimates of the witnesses placed it too high, appellant had the means of showing the fact. This, like the value of property, has frequently to be proved by the opinion of witnesses. When a party has failed to perform his contract the other party has a right to recover such damages as he sustains, and,: in this case, when .appellant failed to perform his agreement, he became liable to-appellee..for such sum of money as he lost thereby. Having purchased them at six cents per pound, if they afterward rose to eight or nine cents, appellee was eUtitled to recover the difference in the price at -which he purchased and that at which they could have been sold. The evidence showed that the seventy head would have averaged 1,250 pounds on the 15th of February, and that on the 13th of March such cattle were worth, at Camp Point, from seven and one-half to nine cents per pound. The jury found a verdict for $1,313.50, which is a trifle1 over eight cents per pound. The evidence as to what the' cattle would have probably increased up-to the 13th of March was, evidently, wholly disregarded by the jury, and, consequently, did appellant no injury.

The law never requires the performance of a useless act. And if appellant placed it beyond his power to perform his part of the contract, by selling the cattle before the time expired at which appellee was to elect when-he would receive them, then a demand would have been useless, and, being useless, he was not required to make it. Mor was he, for the same reason, bound to make a tender of the price. He was only bound to show that he was ready and willing to perform, on his part, to entitle him to recover, and this he appears to have proved.

We do not see that the seventh instruction given for appellee authorized the jury to decide legal questions. The court had instructed them on such questions, and it .informed-them that they should decide all questions according to .the preponderance of the evidence. If they obeyed this instruction they could decide no legal question, as it only submits facts for their determination. We are unable to perceive any error in any of the instructions given for appellee, as they announce correct legal principles.

The instructions given for appellant seem to cover and correctly state the law as applicable to his case. And, under them, the jury were left to consider the evidence and determine whether appellant was liable; and, from what has been said, it will be seen that there was no error committed by refusing his first, third and sixth instructions, and they were properly • refused.

The judgment of the court below is affirmed.

Judgment affirmed.