Opinion by

The plaintiff was the owner of a tract of land in Indiana county which is underlaid by the Pittsburg vein of coal. The plaintiff owned the coal underlying two acres of his land, and title to the coal underlying the remainder of the tract was in the defendant company. The defendant company in its mining operations, in the years 1908 and 1909, drove four entries or headings through the coal owned by the plaintiff, without the consent of the latter. The plaintiff brought this action to recover *111damages for the trespass, averring that the defendant company had knowingly mined and converted the coal taken and that he was entitled to treble damages for the same, and averring, also, that the removal of the coal taken had caused an injury to the surface, through the loss of springs, and to the remaining coal, because of the manner in which the entries were cut through it. The plaintiff recovered a verdict and judgment in the court below and the defendant appeals.

The first specification of error refers to the admission of testimony as to the value at the pit mouth of the coal taken. We are of opinion that the admission of this testimony worked no harm to the cause of the defendant. The witness, in connection with the testimony complained of, testified to the cost of mining and putting the coal at the pit mouth. This testimony was offered merely for the purpose of showing the familiarity of the witness with the business as conducted in that locality and the elements which he considered in his estimate of the value of the coal in place, which he had previously given, without objection by the defendant. The sum total of the testimony of this witness was that this coal was worth one cent per bushel, or twenty-six cents per ton, in place. “It is perfectly clear that the general selling value of coal by the acre in the neighborhood would be a very uncertain standard by which to measure the value of one or two acres reserved for a particular purpose. A few acres so reserved would have no general selling value in the neighborhood. Under these circumstances the learned court below allowed plaintiffs to prove the value of the coal at the pit mouth, from which was deducted the cost of mining and transporting it to that point, the difference being a measure of the value of the coal in place. There was also evidence of the royalty value of the coal in place, that is to say, ten cents a ton, the amount fixed under the terms of the lease. The effort of the trial judge was to require the parties to prove the value of the coal in *112place by the best evidence available under the circumstances:” Little v. Greek, 233 Pa. 534. The witness was competent and the interests of the appellant were properly safeguarded. All the evidence in the case, both of plaintiff and defendant, clearly established that this coal, by reason of its location, its proximity to mining operations and its accessibility to market, had a present market value on the royalty basis, and that it had a market value for operating purposes at a price per ton. The only evidence offered by the defendant as to the value of this coal in place was upon the basis of a royalty of so much per ton. The evidence thus establishing that the coal in place had a royalty value and there being no testimony as to its value upon any other basis, it was proper for the court to submit the case to the jury upon the theory upon which it had been tried, both by appellant and appellee: Trustees of the Proprietors of Kingston v. Lehigh Valley Coal Co., recently decided by the Supreme Court and not yet reported. There was in the present case but little conflict between the testimony of the witnesses for the plaintiff and those for the defendant, as to the value of a ton of coal in place, in that locality. They all agreed that it was worth one cent per bushel, or twenty-six cents per ton, the only conflict in the testimony being that some of the witnesses for the defendant testified that it meant “one ton of 'forked coal/ that is coal from which the slack has been separated.” Said witnesses also testified that by such separation, two-thirds of the coal only is considered marketable. The court submitted the question raised by the conflict of testimony, upon this point, to the jury in a manner of which the defendant does not complain. The question of the value of the coal in place having been submitted to the jury in this manner, we are convinced that the first specification of error is without merit.

The second specification of error complains that R. H. Wilson, a mining engineer, was permitted to testify *113as to the amount of coal taken, without having shown that he had made sufficient measurements. The witness testified that he had made measurements at various places in the mine and that as to two of the entries to which access could not be had because of the amount of water in them, his calculation was based upon the maps of the workings furnished him by the defendant company. These maps of the workings had been made by this appellant and had been furnished to the witness, as the representative of the plaintiff, for the very purpose of showing what coal they had taken out. The maps having been so furnished, it was entirely competent for the engineer employed by the plaintiff to use them as the basis of his calculations of the amount of coal involved by the workings which they represented, particularly in view of the fact that some of the entries which they had wrongfully made could not be measured because of the amount of water standing in them. The second specification of error is overruled.

The plaintiff had in his statement averred that in addition to damages for the coal actually taken he was entitled to recover for depreciation in the value of the coal which remained and the loss of the springs upon the surface. The value of this two acres of coal to the plaintiff, who owned the surface also, manifestly depended upon what effect the removal of the coal would have upon the surface. If the removal of the coal would damage the surface to an amount greater than the price that could be obtained for the coal, then it is manifest that the coal which remained in place had no market value, either before or after the trespass by the defendant. The testimony which is the subject of the third specification of error did not, therefore, prejudice the cause of the defendant. When counsel for plaintiff asked the witness the question, “Q. What is it worth in the market considering the fact that the surface must be supported?” he probably expected the witness to *114answer that the coal had some value, even if it was made subject to the support of the surface. The answer of the witness, however, was, “If the surface is to be supported which the question presumes, then, of course, the coal has no market value, because it must remain there.” If the jury accepted the opinion of this witness as correct, then they certainly would not allow the plaintiff damages for the deterioration of the market value of coal which had no market value, because it must remain in place to support the surface. The third specification of error is overruled.

If the coal which remained in place had a market value greater than the amount of damages which its removal would cause to the surface, then the plaintiff was entitled to recover for any depreciation in that market value which had been caused by the manner in which the headings of the defendant’s mine had been driven through it. If the mining operations of the defendant had so cut up this two acres of coal owned by the plaintiff as to impair the facility with which it could have been mined, and if the workings of the defendant had filled with water, that might have an effect upon the market value of the remaining coal, and it was competent for the plaintiff to show that fact by an engineer familiar with mining operations. The fourth, sixth and eighth specifications of error are dismissed.

The defendant company admitted that it had mined 263 tons of coal out of the headings 3 and 4 with knowledge that said coal was the property of the plaintiff, but contended that the headings Nos. 1 and 2 had been driven through plaintiff’s coal- without knowledge on the part of the defendant that it was trespassing. The learned judge of the court below in instructing the jury' made a slight slip in referring to the position of the defendant, and said: “The defendant contends that it took out 263 tons of coal from the headings 1 and 2, without knowledge that there was encroachment upon the plaintiff’s land.” The 263 tons which the defend*115ant admits that it took with knowledge of the ownership by plaintiff was not taken out of the headings 1 and 2, but was taken from. 3 and 4. The amount of coal which the defendant asserted that it took before it acquired knowledge of the fact that it was trespassing was considerably more than 263 tons, and the statement of the court was, therefore, not strictly accurate. But a judgment is not to be reversed because of a slight inaccuracy in the statement of testimony, which does not go to the real merits of the controversy. The attention of the court should have been at the time directed to this mistake, and it would have no doubt been promptly corrected. The defendant having permitted this mistake of recital of fact by the court below to go unchallenged, must be presumed to have considered it of no importance, and cannot now be heard to assert that the judgment should be reversed because of it. The fifth specification of error is dismissed. If the surface of plaintiff’s land had been injured by the removal of this coal by the defendant, then he was entitled to recover not only for the coal taken but for the injury to the surface. The plaintiff had testified distinctly that two springs upon his land had been destroyed by reason of the wrongful removal of his coal. He was contradicted upon this point by a number of witnesses. The court could not undertake to pass upon this contradictory testimony as a matter of law, the question was one of fact for the jury. The court left the question to the jury, calling attention to the testimony of the witnesses on behalf of the defendant who contradicted the testimony of the plaintiff, upon this point, and in conclusion saying: “The jury cannot guess upon what the plaintiff’s damage would be. If they cannot find such evidence as will satisfy their minds, they will be justified in refusing the item altogether.” The seventh specification of error is dismissed. The offer of testimony, the rejection of which is the subject of the ninth specification of error, was properly excluded. The offer was to *116show that the coal in a certain old mine had not deteriorated from being exposed to the air. The testimony of the witness had not shown that the mine to which the offer of testimony referred was flooded with water, as were the headings driven through plaintiff’s coal by the defendant. The offer was not to show the general effect, upon the coal remaining, of opening entries through a body of coal, it was to show the effect in one particular old mine, without attempting to show that the conditions were the same as those affecting the body of coal involved in this case.

The judgment is affirmed.