Long bars or bolts, with a padlock on the end, on which iron shackles could slide. They were used on board ship to confine the legs of prisoners in a similar manner to putting someone in the stocks. It was a punishment usually known on board as putting a man in irons and continued in use, particularly in American sailing ships, until the latter half of the 19th century. There are examples of bilboes in the Tower of London, taken out of ships of the Spanish Armada. Thus Shakespeare's Hamlet, musing on a forthcoming fight:That would not let me sleep; methought I layWorse than the mutines in the bilboes.The name originates from the steel which was forged at Bilbao, in Spain, at that time reckoned to be the finest in Europe.