When the officers sent by the Incas made their inspection, they entered a province and ascertained, by means of the _quipus_, the number of men and women, of old and young. Then they took account of the mines of gold and silver, and, with so many thousand Indians at work, the quantity that should be extracted was fixed. An order was given that such quantity should be delivered to the overseers. As those who were employed to work at the extraction of silver could not attend to the cultivation of their fields, the Inca imposed the duty upon the neighbouring province to find labour for the sowing and reaping of the crops of the miners. If the mining province was large, its own inhabitants were able both to carry on the mining works and to cultivate the ground. In case one of the miners fell ill, it was arranged that he should return to his home, and that another should take his place. No one was employed in the mines who was not married, because the wives had to supply their food and liquor; besides which, arrangements were made to send sufficient provisions to the mines. In this manner, although men might be at the mines all their lives, they were not overworked. Besides, there was provision to rest for certain days in each month, for their festivals and for pleasure. But in fact the same Indians did not always remain at the mines; for there were periodical reliefs. The Incas so arranged the mining industry, that they extracted great abundance of gold and silver throughout the empire, and there must have been years when more than fifty thousand _arrobas_ of silver and fifteen thousand of gold were produced. It was always used for the royal service. The metal was brought to the principal place of the province, and in the manner that the mines were worked in one district in the same way were they ordered in all the others throughout the empire. If there were provinces where no metal could be extracted as a tribute, the people paid taxes in smaller things, and in women and boys, who were taken from the villages without causing any discontent. For if a man had an only child it was not taken, but if he had three or four children, one was required in payment of his dues.