delivered the opinion of the court,
It cannot be doubted that the recognizance in suit is such an instrument as entitles plaintiff to judgment for want of an affidavit of defence, and hence there is no merit in the first suggestion contained in defendant’s affidavit; nor is there any merit in the averment that, pending the original proceeding in court, payments were made on account of the claim for rent. In the absence of any allegation to the contrary, the presumption is that the payments were duly credited and the verdict rendered for the residue. The record of the original proceeding shows a verdict and judgment thereon in favor of plaintiff for possession of the demised premises and $200 rent in arrear. No writ of error having been taken to that judgment, it is final and conclusive as to the amount of rent.
The only remaining ground of defence set up in the affidavit is, that defendant was released from liability as bail by the amendment allowed on trial of the original landlord and tenant proceeding commenced by Joseph and Mary J. Haekett against the parties for whom defendant in this suit became bail. After the case was removed by appeal to the Common Pleas, it was discovered that by mistake Mary J. Plackett had been improperly joined as co-plaintiff, and by leave of court the record was amended bjr striking out her name. The amendment was clearly authorized and properly allowed: Kaylor v. Shafiher, 12 Harris, 489; Schollenberger v. Seldonridge, 13 Wright, S3; Cochran v. Arnold, 8 P. E. Smith, 399; Wescott v. Edmunds, 18 Id., 34. Whenever it appears that a mistake has occurred, it is the duty of the court to correct it, taking care that the. amendment be not used for the purpose of introducing a cause of action substantially different from that on which the suit was actually though informally brought.
The amendment in this case was clearly one of the legal *295incidents of trial which defendant is presumed to have contemplated when lie became bail, and hence he cannot claim that he was thereby released from the liability he assumed. When a person becomes surety for another in a judicial proceeding, there is at least an implied understanding that it shall be conducted according to the established course of practice in such cases. The statutes regulating amendments, as well as other incidents of trial, are as much a part of the contract, in the contemplation of the parties thereto, as if they were embodied in the condition of the bond or recognizance: Jamieson v. Capron, 14 Norris, 15.
As the case now stands, the affidavit of defence is insufficient, and plaintiff is entitled to judgment for the amount claimed by her testator.
Record remitted to the court below with direction to enter judgment against defendant for $150, the amount of his recognizance, with interest from July 30, 1883, the date of suit, unless other legal or equitable cause be shown to said court why such judgment should not be so entered.