Tourniquet
an instrument for compressing the main artery of the thigh or arm, either for the purpose of preventing too great a loss of blood in amputation, or to check dangerous hemorrhage from accidental wounds or to stop the circulation through an aneurism, For the last purpose special forms of tourniquet are required, which do not compress the whole limb.
The common tourniquet consists of three parts-viz. (1) a pad to compress the artery; (2) a strong band which is buckled round the limb; and (3) a bridge-like contrivance over which the band passes, with a screw whose action raises the bridge and consequently tightens the band. The credit of the invention of this most useful instrument is usually ascribed to the French surgeon Morel, who, in 1674, used a stick passed beneath bandage, and turned round so as to twist it up to the requisite degree of tightness, as a means of preventing the undue loss of arterial blood in amputations of the limbs. A much improved screw tourniquet was invented by Petit in 1718, the same in principle as that described above. Many surgeons now use in preference a strong elastic band, wound two or three times round the limb-a method first introduced by Esmarch.