Porte-Lacs were designed to introduce and carry a string of hemp or silk and advance it around the trunk of the fetus in cases of shoulder and other mal-presentations where extraction required transection of the fetal torso by rapid back-and-forth movement of a chain saw or other similar device. A splendid and rare example of Tarnier’s Porte-lac a Ressort, as illustrated by Witkowski, unsigned, ebony handle.