On the Thames River to London were large ships with cargoes; small boats rowed by tough boatmen offering passage for a penny; small private barges of great men with carved wood, gay banners, and oarsmen with velvet gowns; the banks covered with masts and tackle; the nineteen arch London Bridge supporting a street of shops and houses and a drawbridge in the middle; quays; warehouses, and great cranes lifting bales from ship to wharf. Merchant guilds which imported or exported each had their own wharves and warehouses. Downstream, pirates hung on gallows at the low-water mark to remain until three tides had overflowed their bodies. A climate change of about 1 1/2 degree Celcius lower caused the Thames to regularly freeze over in winter. The large scale of London trade promoted the specialization of the manufacturer versus the merchant versus the shipper. Merchants had enough wealth to make loans to the government or for new commercial enterprises. Local reputation on general, depended upon a combination of wealth, trustworthiness of character, and public spirit; it rose and fell with business success. Some London merchants were knighted by the King. Many bought country estates and turned themselves into gentry. The king granted London all common soils, improvements, wastes, streets, and ways in London and in the adjacent waters of the Thames River and all the profits and rents to be derived therefrom. Later the king granted London the liberty to purchase lands and tenements worth up to 2,667s. yearly. With this power, London had obtained all the essential features of a corporation: a seal, the right to make by-laws, the power to purchase lands and hold them "to them and their successors" (not simply their heirs, which is an individual and hereditary succession only), the power to sue and be sued in its own name, and the perpetual succession implied in the power of filling up vacancies by election. Since these powers were not granted by charters, London is a corporation by prescription. In 1446, the liverymen obtained the right with the council to elect the mayor, the sheriff, and certain other corporate officers.