The trap has a setting mechanism that operates completely automatic. The mouse (or rat) walks into the trap over a tripping mechanism that closes the door behind it. The animal in that moment can only climb upwards. At the top there is another tripping mechanism that makes the animal slide into a barrel of water and at the same time opens the front door again: the trap is ready for another victim. In this way dozens of animals can be caught and killed accourding to the publicity of that time.
