is where a commission or patent is granted by the king in the nature of a letter, to certain persons, who are thereby appointed his justices, or to two or three of them, authorising them to deliver his gaol, at such a place, of the prisoners contained therein; and for that end it commands them to meet at such a place, at the time they themselves shall appoint, when the sheriff of the county is commanded to bring all the prisoners in the gaol before them, &c.