Opinion by
Beaver, J.,The plaintiff brought his suit before a justice of the peace, based upon four separate and distinct items, all of them arising under contracts made with the defendants, as to which the justice had jurisdiction and for all of which he rendered judgment in default of appearance against the defendants. After judgment and before the statutory period for taking an appeal had passed, “defendants appear and pay $2.75, the amount-for grubbing and assisting surveying ground, and appeal from the rest of the above judgment.”
*58The specifications of error are numerous but are all practically rooted in one question, Can a defendant, against whom a judgment has been legally rendered by a justice of the peace, pay so much of the said judgment as he admits to be due and appeal from the remainder thereof ?
“ One rule to be deduced from the cases unquestionably is that on appeal, though the form of the suit may be sometimes changed, yet the substance of the plaintiff’s demand — the cause of action — must be in court identically the same as before the justice:” Caldwell v. Thompson, 1 Rawle, 370. “It is true that for certain purposes a trial in the common pleas after an appeal from a justice is de novo but it is, nevertheless, a trial of the same case. The mechanical work of the trial, such as the formation of the proper issue, the production of the testimony and the decision of the questions involved is de novo but the cause of action remains the same: ” Diehm v. Snell, 119 Pa. 316. The object of a trial on an appeal is to determine whether or not the plaintiff’s suit was rightfully and rightly brought before the justice of the peace. The trial of the appeal must, therefore, relate to the period at which the suit was originally brought. Neither party can change the issue. The cases above referred to relate, it is true, to the act of the plaintiff and determine conclusively that the plaintiff cannot, on the trial of the appeal, change the cause of action, either as to character or amount, as originally brought, but the general principle applies as much to the defendant as to the plaintiff. If the defendant can, after judgment, pay so much thereof as he may acknowledge to be due or as may, in his judgment, be legally recoverable against him and appeal only from the remainder of the judgment, he thereby changes the cause of action and practically admits the right of the plaintiff to maintain his suit for the amount paid. Pie may thereby, if such a course is permissible, involve the plaintiff in the costs of an action essentially different from that from which the appeal is taken. There is not only no statutory warrant for such a proceeding but it is subversive of the general principle clearly set forth in the authorities cited and of the general provisions relating to appeals contained in the Act of March 20, 1810, 5 Sm. L. 161.
■ The defendants could, under the provisions of the Act of March 12, 1867, P. L. 35, at any time before trial in court, *59have made a tender to the plaintiff equal to the amount they admitted to be due, with all lawful costs incurred in said action up to the date of making such tender. This act was doubtless passed to secure to the defendants the practical results at which they aimed, but we know of no statutory authority and have been referred to none which authorizes a defendant to reach a similar result by the mode adopted in the present case.
It follows, from what has been said, that the appeal was illegally taken and that all subsequent proceedings are of no effect. Judgment reversed and the appeal from the judgment of the justice stricken off.