Letter slot

late 19th century

Letter slots allow discrete access to a building's interior. A metal plate, such as this was affixed over an opening on an exterior door or wall. The 4 1/2-inch long opening makes a tight fit for today's business-sized envelopes. The hinged flap marked "Letters" lifts upwards, requiring the letter carrier to manually open the slot. Letters that were dropped through simply fell on the floor or were caught in a basket attached indoors.