"The obstacle which has prevented the construction of the railway," said he, in answer to Dr. Bronson's question, "was one not easy to foresee. The engineers who visited the place, and made a preliminary examination of the route, did not remain long enough to suffer from the pestilential atmosphere, and consequently they did not know of it. But when the labor actually began the case was different, the men died off very fast, and it soon took all the time of those who could get about to care for the sufferers and bury the dead. "There are no engineering difficulties to prevent the construction of the line, as the country is only slightly undulating, and there are but few rivers to cross. But it appears that there are terrible fevers lurking wherever cataracts in tropical countries fall over granite rocks. There are hollows between the rocks that retain the waters when the rivers fall from their highest levels, and these waters become stagnant pools. Vegetation decays in these pools, and they give off miasmatic vapors under the heat of the tropical sun. Europeans die rapidly in consequence, and even the negroes and natives cannot long endure the poisonous atmosphere. [Illustration: BURIED IN THE TROPICAL FOREST.] "Mr. Davis, the English engineer who came here to superintend the work, endeavored to improve the place by blowing up the rocks at the pools, and where this could not be done he set his men to pumping out the water in order to drain off the surplus and arrest the decay. He accomplished a good deal in this way, but fell a victim to the fevers, and died in spite of all the efforts of the doctor to save him. His grave is in the forest, just behind the village. "The loss of the chief disheartened his subordinates, and all who could leave made haste to do so. The Mojos Indians and the Caripunas do not appear to be affected by the climate, but they cannot be induced to work at railway building, preferring employment in transporting goods and boats around the falls." The information thus obtained made the little party of strangers desirous of leaving San Antonio as soon as possible. The Indians took advantage of their desire by demanding a high price for carrying them down the river. A steamer was expected to arrive in a few days, but they were unwilling to wait there, wisely preferring to spend the time in a less unhealthy locality. Dr. Bronson told Manuel to engage a boat at any price, on the condition that it would leave at once, and the negotiation was speedily made. Three hours after the conversation with the Brazilian the boat with our friends and their baggage pushed off from shore, and floated on the current of the Madeira. The fever-stricken residents of San Antonio gazed sadly after them, and mourned the fortune that detained them in that deadly place.