These were by no means all the charges imposed on the guilds. They had further to guarantee certain public services. To the building guilds was assigned the provision of safeguards against fire; to the doctors' and barber-surgeons' guilds, the care of the sick poor and of the hospitals; to all, or nearly all, the assessment of certain taxes, the policing of the streets, and sometimes the defence of the ramparts. In Paris, where the nights were as unsafe as they were ill-lit, every guild in turn furnished, according to its importance, a certain number of men to patrol the streets and keep guard, from the ringing of curfew to the break of day, when the sergeant of the Châtelet sounded the end of the watch. The same custom was to be found in most of the free towns. A few guilds only were exempt from keeping guard, either on account of their finances or because it was considered that they had to render other services. Such, for example, were the goldsmiths, archers, haberdashers, judges, doctors, professors, etc. On the other hand, some guilds were under special regulations, _e.g._ the provision guilds. The fear of scarcity, owing to the frequency of bad harvests or war and also to the permanent difficulty of communication and transport, was a perpetual menace to the towns. Their policy in this matter was nearly always that of a besieged city. The consequent legislation was, above all, communal, and was inspired by two fundamental principles: first, that on the Commune devolved the duty of seeing that the inhabitants were healthy and well fed; secondly, that the Commune, when it was short of money, had a convenient resource in the taxation of the necessaries of daily life.