The thumbscrew, or pilliwinks, is a torture instrument which was used in medieval Europe. It is a simple vise, sometimes with protruding studs on the interior surfaces. The victim's thumbs or fingers were placed in the vise and slowly crushed. The thumbscrew was also applied to crush prisoners' toes, while larger, heavier devices based on the same design principle were applied to destroy knees and elbows.
This torture was extremely painful and usually forced out confessions of the victim.
As late as the mid-18th Century, the ex-slave Olaudah Equiano testified to having witnessed the use of thumbscrews to torture slaves on a Virginia plantation (included in his autobiography "The Interesting Narrative of the Life of Olaudah Equiano").
Pilliwinks or pyrwykes may also have been used to straighten girls' fingers in medieval and Renaissance England, similar to how braces are used to straighten teeth today. The pyrwykes used for this purpose probably differed from thumbscrews by squeezing the fingers. According to the Tudor historian Eric Ives, Anne Boleyn sent a pair of pyrwykes to the nursemaid looking after her daughter, the future Elizabeth I. Presumably, this device was responsible for Elizabeth's elegant fingers.