On complaints in a District Court charging drunkenness (G. L. c. 272, Section 48), operating a motor vehicle while under the influence of intoxicating liquor (G. L. c. 90, Section 24), operating a motor vehicle negligently so that the lives or safety of the public might be endangered (G. L. c. 90, Section 24), and failure to stop for a police officer (G. L. c. 90, Section 25), the defendant was found guilty. On appeal to the Superior Court, the jury returned a verdict of not guilty on the drunkenness complaint and verdicts of guilty on the others. The cases come here on the defendant's exceptions to the denial of his motions for directed verdicts on the three complaints on which he was convicted. The evidence warranted a finding that the defendant was guilty of operating a motor vehicle while under the influence of intoxicating liquor on a way as defined in G. L. c. 90, Section 1. Commonwealth v. Lyseth, 250 Mass. 555 . Commonwealth v. Leone, 250 Mass. 512 , 515. The evidence was likewise sufficient to warrant a finding that the defendant was guilty of driving a motor vehicle negligently on a way so that the lives or safety of the public might be endangered. Commonwealth v. Leone, supra, at p. 514. The defendant's motions with respect to these two complaints were rightly denied. We are of opinion, however, that the judge ought to have directed a verdict on the complaint charging failure to stop when signaled to do so by a police officer. Essential proof required by the statute was lacking. The evidence failed to show that the officer was in uniform when the signal to stop was given or that he "display[ed] his badge conspicuously on the outside of his outer coat or garment." See Commonwealth v. Sullivan, 311 Mass. 177 , 178. On the complaints charging driving under the influence and driving so as to endanger the exceptions are overruled; on the complaint for failure to stop for a police officer the exceptions are sustained.