delivered the opinion of the court.

This was a suit on a contract by which the plaintiffs agreed to frame and erect fifteen railroad bridges for the defendants on the Illinois division of the Ohio and Mississippi railroad, for a fixed price per foot, lineal measure, to be paid by the defendants. One of the main questions of fact raised by the *134pleadings, was as to the number of feet contained in the work. In support of this issue the plaintiffs read in evidence, against the objections of the defendants, a paper purporting to be a copy of the final estimate of the work by the engineer in charge of that part of the road, showing the number of feet contained in the fifteen bridges. There was no attempt to show where the original estimate was, or to account for its absence. Furthermore, if the non-production of the original had been sufficiently accounted for, the proof that the -paper produced was a copy was wholly insufficient for that purpose. That proof consisted alone of the ex parte, unsworn certificate of an engineer, who succeeded the one who it is assumed made the'measurement.

The court erred in permitting the paper to be read, and for this cause its judgment must be reversed and the cause remanded ; the other judges concurring.