A 19th century hand held trephine made from ebony, brass and blued steel. The two different sized drill bits and stems are detachable and interchangeable. A central pin can be adjusted so that after anchoring the drill bit they can be subsequently retracted so as not to cause damage to the cerebral cortex. In excellent condition noting a superficial small superficial chip at one end of the handle. The instruments are not signed but are of excellent build quality.