In submitting the case to the jury, the trial court charged that it might return a verdict in favor of plaintiffs if it found that defendant failed either (1) to furnish adequate supervision, or (2) to provide a mat underneath the chinning bar. The jury returned a verdict for plaintiff; the court set it aside and dismissed the complaint and the Appellate Division affirmed that disposition.

Although the court was correct in its final decision that the case should not have been submitted to the jury on the first ground, it erred in dismissing the complaint since there was evidence to support the verdict on the second ground. Accordingly, the judgments may not stand. Since, however, no one can know or say on which ground the jury arrived at its verdict, there must be a new trial. (See Clark v. Board of Educ. of City of N. Y., 304 N. Y. 488, 490; Phillipson v. Ninno, 233 N. Y. 223, 226.)

The judgments should be reversed and a new trial granted, with costs to abide the event.

Loughran, Oh. J., Lewis, Conway, Desmond, Dye, Fuld and Froessel, JJ., concur.

Judgments reversed, etc.