1. If a conviction of part of the offence could be a bar to this indictment—a point which we need not now decide—it must be a conviction, and not a mere prosecution. Commonwealth v. Drew, 3 Cush. 279.

2. It is undoubtedly true that a riot cannot ordinarily be committed by one person. It is the acting in concert, the unlawful combination, which constitutes the offence. The direction was strictly correct. Whether the other rioters were named in the indictment, or not, proof of a riot in which any two other persons joined with the defendant was sufficient.

Exceptions overruled.