ANIMAL TRAP
Hermetically seals the animal's head inside a gas chamber.
The animal inserts its head through the front opening and seizes the bait hook. Forward movement of the bait holder trips a pawl, releasing a spring-loaded yoke that descends on the animal's neck while flexible closure members and a curtain draw shut around it, sealing the head inside the body. Simultaneously, a plunger drops onto a cartridge of compressed asphyxiating gas, which discharges through a delivery tube over the animal's head. The animal is asphyxiated, permanently or temporarily depending on the gas selected, without damage to the pelt.
“The device may by selection of the asphyxiating gas used, be arranged for either the immediate dispatch of the animal or for a temporary insensibility. In either instance, the animal will suffer no pain and no wounds will be inflicted which will be painful or cause injury to the fur of the animal.”— Walter J. Lementy, from the specification
And the world did not beat a path to his door.