One method of restraint was known as the Bilboes, which consisted of a long iron bar attached to the floor. Free to slide along the bar were a number of hinged iron rings which were riveted about the ankles of the prisoners, forcing them to sit or lie down until the restraint was released. The word is a corruption of the Spanish town Bilbao, for when the Armada was defeated in 1588, chests of these shackles were found in the galleons, reputedly to pinion English captives. In actual fact similar devices were widely used for naval prisoners on board ship and the Royal Navy was equipped with them until the eighteenth century.
Eventually they found their way to the West Indies, where they were used during the slave trade era. Ten or more slaves would be secured in bilboes, being released each day before being taken to work in the plantations.