According to the Science Museum, London, this item from Henry Wellcome's curiosity collection is a "man catcher… used in Europe in the late 1700s during times of war. The terrifying collar pulled riders off horseback. In peacetime, it is thought the device may have caught and held escaped prisoners." "Man catcher, Germany, 1601-1800" (via Neatorama)
David Pescovitz is Boing Boing's co-editor/managing partner. He's also a research director at Institute for the Future. On Instagram, he's @pesco.