When at times in the river’s narrow water course there are a dozen large steamers lying and a lively business intercourse is everywhere in progress, the scene, in the depth of the primeval forest, creates quite an imposing impression. Hapury is considered already in the district of Alta Acre and from this point, the difficulty of navigation increases, the breadth and volume of water of the river alike decreasing. Very rapidly during long, rainless periods, the river water level lowers and the further progress of the steamers becomes impossible. They must anchor at a convenient place and wait until the river rises again. In lower Acre, where water is more plentiful, such interruptions are less frequent, but in upper Acre they are the rule. The farther the river is ascended the more frequent are these compulsory stoppages, often lasting eight to fourteen days. High-water in the river often lasts but a few days, so that the steamers must stop again. Then too, the many windings of the river make navigation exceedingly difficult. On the upper Acre travel is by day only, boats laying to at night. Following the course of the river, 85 kilometers above Hapury, Igarapé de Bahia is reached, on the Bolivian border and then the little town of Cobija. It is situated on the right bank and belongs to Bolivia, whereas on the left bank, Brazilian territory continues. The steamers here are subject to the Bolivian customs regulations and must pay duty on all goods destined for Bolivia. A large number of the steamers that start from Manáos, go only as far as this or as Hapury, only a few venture to penetrate further and are not deterred by the great loss of time. Above Cobija are some of the most productive rubber sections where there are goods to discharge and rubber to be loaded. A few steamers follow the Bolivian border up to the terminal station, Tacna. Here, as a small affluent from the right, the Taverija flows into the Acre, forming at the same time the boundary between Bolivia and Perú. Bolivia maintains here a small military post, whereas there is only a commissioner for Perú. If the steamer has met with favorable conditions, the trip from Manáos may have been made in a month; ordinarily, however, it takes two or three months. The return trip is made much faster, some steamers, that do not stop, make Manáos from upper Acre in fourteen days. Above Tacna there are but two rubber forest districts or seringaes as they are termed, the Seringal Auristella on the Peruvian side and the Seringal St. Francisco on the Brazilian side. The latter is a very productive and still young rubber forest, farther up the river the fine rubber trees suddenly cease and their output is no longer remunerative. [Illustration: RUBBER TREE AT HAPURY.]