By cocking the trigger on the top of the instrument the eight circular blades are rotated back into the base under intense spring force. When you push the round knurled release button the blades snap through the slotted ways and lacerate the wrist with a vengeance.
The device came to me in great disrepair, well corroded, with the steel hight knob adjuster broken free from the bottom slotted plate that received the blades. A large section of this plate was missing. Using a milling machine, a new plate was created, then soldered in place after which the linear cut-outs were reproduced using a miniature end mili. Once polished, the replaced section can not be detected.
Within 24 hours of President Washingtons rain soaked ride, four of the local physicians argued over the best procedure to take for his cure. In the process they pushed aside his loving caretaker slave and her hot chicken soup and preceded to drain more than 80 oz of blood from him using this little brass devise. The chicken soap would have worked.