delivered the opinion of the Court:

All controverted questions of fact in the case are settled in favor of appellee by the verdict of the jury and the judgment of affirmance in the Appellate Court. The grounds upon which a reversal is now asked, are, that the first and second instructions for appellee were erroneous, and that it was error to refuse the third instruction 'tendered by appellant.

In said first instruction, the court instructed the jury, in substance, that if the teamsters of appellant, by direction of appellant, hauled the lumber which slid over and upon the deceased, to the premises used and occupied as and for a dry-kiln and place for piling and handling such lumber, and that such teamsters unloaded and piled a portion of such lumber without the assistance of others, and unloaded and piled the balance.of such lumber with the voluntary and gratuitous assistance of the witness Honey, and if such lumber was piled by such persons in an unskillful and unsafe way and manner, and by reason' of such unskillful and unsafe piling of such lumber the same fell over and upon the deceased, and killed him, without any negligence or want of ordinary care on his part, then the defendant was guilty. The instruction proceeds upon the hypothesis that the teamsters of appellant unloaded and piled a portion of the lumber without the assistance of others, and unloaded and piled the residue of it with the assistance of Honey. Upon the hypothesis stated, the acts of' unloading and piling a portion of the .lumber were the acts of' appellant, by his teamsters and servants; and the acts of unloading and piling the other portion were the joint acts of' Honey and of appellant, by his same teamsters and servants.. Parties who act in concert, and co-operate in doing a negligent act which causes an injury, are liable, either jointly or severally, to the person injured, for the damage thereby occasioned. The theoretical case stated in the instruction was supported by the evidence, and it imposed a clear legal liability upon appellant, regardless of the fact whether Honey is or is not to be regarded as having been his servant, volunteer or otherwise, in the transactions involved in the suit. We see no valid objection to the instruction, and hold it was not error to give it.

The relation of master and servant existed between appellant and his teamsters, and it was within the scope of the employment of the latter not only to haul the lumber to the yard, but to deliver it there, the platform being full, by unloading and piling it upon the ground. This being so, and it being immaterial whether Honey was or was not a servant of appellant, the rulings of the trial court in refusing the third instruction asked by appellant and giving the second instruction for appellee, and without reference to the question of the propriety of such rulings, affords no ground for reversal, as whatever was the relation of Honey to appellant, the rule of respondeat superior was applicable to the ease.

We find no manifest error in the ease. The judgment of' the Appellate Court is affirmed.

' Judgment affirmed.

Mr. Justice Bailey, having heard this cause in the Appellate Court, took no part in its decision.