The new provinces rapidly increased in population and prosperity, which was temporarily interrupted by a drought between the years 1744 and 1749. During this period the streams dried up, and in consequence of the severe heat the woods caught fire. A great mortality ensued; whilst the people were alarmed at mid-day by a sound as if of thunder beneath their feet, which was followed by several shocks of earthquake. This disturbance, however, was merely temporary; and in one year more than fifteen hundred persons passed from _Goyaz_ to _Matto-Grosso_, bringing droves of cattle and horses. A salt lake was opportunely discovered, to remedy the distress which had been occasioned from the want of that article. The Portuguese in _Brazil_ had shown exemplary enterprise in pushing forward their settlement along the various streams which form the tributaries of the _Amazons_; and there were in consequence some disputes with Spain concerning the boundaries. They had even occasioned some fears in the minds of the Spanish authorities as to the safety of _Peru_. They had likewise, by their inland explorations by water, ascertained that there was a communication by water between the _Amazons_ and the Orinoco, they having from the former reached the Spanish missions on the latter river. By the middle of the eighteenth century no hostile tribes remained on the banks of the _Amazons_ throughout the entire course of that stream; such as had not submitted to the missionaries had retired into the interior. Some Indians, being terrified of pursuit, did not feel themselves in safety until they had reached the French territory of _Guayana_, where they were well received and encouraged to settle. It is stated that the Portuguese missions on the _Amazons_ were in a more flourishing condition than were those of the Spaniards on the upper part of the same river or its tributaries. The reason is to be found in the fact that whereas the former depended for their communications and supplies upon the flourishing settlement of _Belem_ or _Pará_, the latter were forbidden to hold any communication with their Portuguese neighbours, and had to be supplied by the long and difficult overland route from _Quito_, which place was itself a six days’ mountainous journey from the sea-coast. The city of _Pará_ itself is stated by a French traveller[14] to have presented at this period the aspect of an European town, with regular streets of well-built stone houses and with magnificent churches. During thirty years it had been gradually rebuilt; whilst by clearing the country and converting woodland into pasture the healthiness of the city had been made to undergo a corresponding improvement. It should be remarked that about the year 1730 the plague of small-pox was here stayed amongst the Indians by the introduction of inoculation at the hands of a Carmelite missionary.