6. When any cards, dice, gaming-table, cloth, boards or other instruments of gaming are found in any house, tent, room, space or walled enclosure entered or searched under the provisions of the last preceding section, or about the person of any of those who are found therein, it shall be evidence, until the contrary is made to appear, that such house, tent, room, space or walled enclosure is used as a common gaming-house, and that the persons found therein were there present for the purpose of gaming, although no play was actually seen by the Magistrate or police-officer, or by any person acting under the authority of either of them.