Dating to the late 1700s this is a superb example of a bistoury cache by Savigny used for the extraction of bladder stones. The instrument has been well protected and remains pristine. The polished steel lever which opens the blade is attractively crosshatched as is the spring loaded release button which secures the lever within the ebony handle allowing the blade to be fixed in an open position. There is a second adjustment possible using the pivot screw which allows the blade to be moved forwards and backwards a few mm within a steel loop. The stem is signed "Zavigny". The beautifully fitted case is remarkable in its own right being made from sharkskin which is also perfect throughout. It is lined with red velvet and silk and the hinges and catches are original and in good working order.