William Crossing in his Guide to Dartmoor states that a well known Dartmoor guide (James Perrott[2]) placed a bottle for visiting cards at Cranmere Pool[3] on the northern moor in 1854.[4] From this hikers on the moors began to leave a letter or postcard inside a box along the trail (sometimes addressed to themselves, sometimes a friend or relative)—hence the name "letterboxing". The next person to discover the site would collect the postcards and post them. In 1938 a plaque and letterbox in Crossing's memory were placed at Duck's Pool on southern Dartmoor.[5][6][7]