At the trial the plaintiff proved that the excavation in the street was made by an independent contractor under a permit from the city. He might have done better by stopping with the proof of his own case. The argument in support of this appeal is that the city was not relieved from liability because no lawful permit had been obtained. This is a clear shifting of position because of after-discovered law and raises a question not involved in the trial. The case was properly tried on the issue raised, and the judgment is affirmed on the opinion of the learned judge of the commoxi pleas. '