a tribute rated upon every town, which formerly was wont to be paid annually into the King's-exchequer, but now not without consent of parliament; it differs from a subsidy in this, that it is always certain, as set down in the exchequer-book, and in general levied of every town, and not particularly of every man, &c. The ancient way of levying taxes was by tenths and fifteenths, afterwards by subsidies and royal aids, and at length by a pound rate; the former of these were all upon the person and personal estate, but the last upon lands and rents.