There is no such offence as obstructing a patrol in the per-formauee of their duty. To assault a public officer in the discharge of his duty, is an aggravated misdemeanor; but the assault is the offence, and the fact of its being committed on a public officer is mere aggravation; and so, to assault a patrol would be a misdemeanor, and it might also be a misdemeanor to rescue from them a slave lawfully apprehended; but so long as the opposition to a patrol consists in mere words, an indictment will not lie.