The great importation of negroes into _Minas Geraes_ gave occasion to fears which were not entertained elsewhere in _Brazil_, and in consequence an order was issued forbidding the formation of free blacks into separate companies, and requiring that they should be mixed with white soldiers. No person who was a mulatto within the fourth degree might be an ordinary judge or hold any municipal office in _Minas Geraes_. The mode of mining had now undergone a considerable alteration. Instead of opening cuttings and carrying the produce in bulk to be washed, water was conveyed to the mining ground, and, washing away the mould, broke up the blocks in pits or wooden troughs, thus saving a great expenditure of labour. As water-power thus became a valuable property, those in possession of water-courses derived great advantages therefrom. Their pretensions were, however, so extravagant that it was found necessary to establish a set of laws respecting the distribution of the water. The discovery of the mines had brought about so great an increase of wealth that the jealous restrictions against the immigration of foreigners into _Brazil_ were rendered more stringent than ever. Not only were they forbidden to enter the country, but no person might embark for it unless he were appointed to an office there, or unless he were a servant of Portuguese birth accompanying his master. Even Portuguese must be provided with passports; and the clergy were likewise under restrictions. The _Paulistas_, being greatly outnumbered by strangers in _Minas Geraes_, sought and found a new field for their energies. It was to the enterprise of one of this class of men, named Pascoal Cabral, that was due the discovery of the mines of _Cuyabá_ in the centre of the Continent,--mines which should more naturally have fallen to the lot of the Spaniards from _Paraguay_ or from _Santa Cruz de la Sierra_. The journey thither from _S. Paulo_ was long and arduous, and was further attended with no slight risk, leading the traveller through the native country of the fierce _Puayaguas_. These people rendered the journey to _Cuyabá_ so dangerous that, when a colony had been established there, a strongly-armed vessel was sent thence to await the annual caravan of traders at the _Paraguay_ river.