an ancient customary duty or toll, for weighing of wool. According to Fleta, trona is a beam to weigh with, mentioned in the stat. Westm. 2. cap. 25. And tronage was used for the weighing wool in a staple or public mart, by a common trona or beam; which, for the tronage of wool in London, was fixed at Leaden-Hall. The mayor and commonalty of London are ordained keepers of the beams and weights for weighing merchants commodities, with power to affix clerks and porters, &c. of the great beam and balance; which weighing of goods and wares is called tronage; and no stranger shall buy any goods in London before they are weighed at the king's beam, on pain of forfeiture.