The Ring-Release Snap Hook: Change Your Grip and the Dog Frees Itself

"An object of the invention is to provide a leash for securing animals, particularly hounds, and which permits of readily releasing the animal from leash." "When it is desired to suddenly release the animal from leash, the hand is removed from the handle 12 and arranged to grasp the upper end of the supplementary strap 13, thus in view of the pull exerted by the animal causing the actuating member 25 to slide upwardly on the snap hook and bear against the faces of the shanks 26". "The animal can be released from leash without necessitating any manual operation on the part of the operator other than the changing of the grip of the hand from the handle 12 to the supplementary strap 13."

Draw two pieces on plywood, each with a jaw curled inward at the bottom, a shank at the top and a tab reaching to the centre line between them. Cut them with the coping saw and bolt the two tabs together with a washer between, so each piece stays on its own side like the two halves of a clothespin: the jaws meet below the bolt and the shanks spread apart above it at about 10 degrees each. Stretch a rubber band round the jaws so it holds them shut. Bend steel wire into a ring that slides freely on the shanks just above the bolt. Tie paracord to the ring. Tie a cord round the bolt and fix it to the bench, and hook a loop of cord in the jaws as the collar. Pull the shanks together with the spring scale to read the force that just opens the jaws. Then pull the ring's cord up the shanks, away from the bolt, with the spring scale and read the pull when the jaws open. Measure the shank angle with the protractor and compare with the notebook. Look at a real snap hook and find its spring and gate.

**Hermann Kunze** of Philadelphia filed US 1,161,870 on 23 April 1915; it was patented 30 November 1915. He wrote that it was particularly adapted for "what are commonly known as police dogs". **Honest limits.** The notebook treats the ring as a smooth wedge and the spring force as constant. Angles and forces are examples. Your measured pull is the result.