Torture with the ‘boot’.
433
The BOOT [...] is a form of torture used to extract from criminals a confession
of their crimes; it consists in certain places of a sort of box or stocking
made of parchment, wetted & applied to the leg of the victim; the encased
leg is then subjected to heat, causing the extreme shrinking of the boot,
quickly crushing the leg, & inflicting agonising pain.
There is another type of torture also called the boot, which consists of four sturdy planks of wood bound around the legs with rope. Two of the planks are placed between the criminal’s legs, & the other two on the outside of the legs, also bound tightly together with rope; a wedge is then pounded between the planks inside the legs, causing the planks to spread & the rope to tighten; the pressure of the pounded wedge reaches the leg bones & breaks them, or occasions dislocation, which causes horrible pain to the criminal. This form of torture is no longer practised in England: but it still remains in use in France, Scotland, & a number of other countries.
Source: Diderot, Denis et Jean le Rond d'Alembert, "Torture with the ‘boot’, in l'Encyclopédie, ou Dictionnaire Raisonné des Sciences, des Arts et des Métiers " (Paris: Briasson et autres, n.d.), tome II, page 433.