In using the device, the forefinger is passed into the ring and the thumb pressed upon the lever, by which the perforator is raised, and upon reaching a point is deployed by the force of a spring, and, slightly puncturing the skin deposits the virus.  Thus, in a single, easy motion, a vaccination is performed.  “The pain attending its use is so slight, as rarely to awaken a sleeping child, while the operation is rendered much more certain than by other methods.”