A Petit tourniquet, said to have been used by Gillespie on HMS Victory. The Petit tourniquet was named after its inventor, Jean-Louis Petit (1674-1750), and was used to stop exces bleeding during amputation. The belt was pulled tight around the limb above the wound, with the screw over the main artery. Turning the screw compresed the artery and posibly some of the main nerves, helping to numb the pain.
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