law: 6. Finding cards, etc., in suspected houses, to be evidence that such houses are common gaming- houses.
  When any cards, dice, gaming-tables, cloths, boards or other instruments of gaming are found in any house, walled enclosure, room or place 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, walled enclosure, room or place, 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 any of his assistants.