Before goods could be sold, those who had the right to weighing and measuring apparatus in their own houses, must have these sealed by the measurers and gaugers’ gild. Others must use the scale of the king or his vassal. Most goods were sold on Friday and Saturday, when the merchants shut up shop and went to the _Halles_ where markets were held. As a rule, the gilds were opposed to the hawking of their goods—_col-portage_; they preferred the more regular custom of the stalls of the market. Here, too, they succeeded in legalizing their privileges against foreigners. For example, the bakers succeeded in preventing the sale of all ‘foreign’ bread in the city except on Saturdays. The municipality also watched after its own interests in the interests of the crafts. Merchants were forbidden to leave the city before the opening of the Fairs, and sales must be transacted only in the square of the _Halles_ after a stroke from the great bell. The craft organizations themselves were much afraid of possible monopolies. The weavers, dyers and fullers are expressly forbidden to enter into combinations to fix a price on goods or a monopoly on materials “so as to prevent the people of the gild from having work according to their means.” The retailers of produce were forbidden to arrange for commodities in advance. “Retailers ought not to buy in advance of any merchant carriage-loads or consignments of eggs and cheeses, deliverable at his next trip, or after any delay whatsoever”; such transactions are wrong because they offer too much uncertainty and too many frauds in the conditions of delivery. The mediaeval man feared ‘corners,’ for he felt “the rich will sell back everything, as dear as it pleases them to do.” In the market “good form” must be observed between members of the same gild. One member must not intrude before a sale is consummated. “If anyone is in front of the stall or window of a cook to buy or bargain with the said cook, and if any of the other cooks call him before he has left the stall or window of his own will,” the fine will be 5 _sous_. For the privileges implied in the gild structure, the feudal authorities demanded a return in the form of taxes. The gild-masters bore the burden not only of the civil taxes which all citizens shared, such as the _taille_, the _conduits_ and _péages_ (tolls), but also special commercial taxes such as the _hauban_, the _tonlieu_, and the _coutume_.