342 The Andes and the Amazons. 



southeast to a northeast direction. This majestic tribu- 

 tary drains an area of 40,000 square leagues. The Low- 

 er Madeira (the part below the rapids), at mean level, 

 carries 14,642 cubic metres of water per second, and 

 has a slope of one metre in 26,490. Its banks are only 

 about twenty -five feet above low-water mark; and as the 

 floods usually rise twenty-eight feet, the country is inun- 

 dated far and wide. The only village below the falls is 

 Borba, a huddle of a dozen huts around a half-finished 

 church. The banks of the upper affluents, as the Mamore, 

 are from thirty to forty feet high, and there we find the 

 most immense agricultural I'egion in the basin of the Am- 

 azons. Of the three great tributaries to the Madeira, the 

 Beni is the most important ; in fact, it is the main source, 

 for it is equal to the Mamore and Guapore together. At 

 its mouth it is 1000 metres wide and fifteen deep, and at 

 mean level discharges 4344 cubic metres per second. The 

 Incas understood and profited by the inexhaustible wealth 

 disclosed and created by this river — the montana of Cara- 

 baya and the carrvpos of the Beni. 



The Madeira is the natural avenue to Bolivia and to the 

 province of Matto-Grosso. It is navigable to San Antonio, 

 a distance of 546 miles.* Here begins a series of rapids, 

 nineteen in number, having a total fall of forty-four fath- 

 oms, above which a steamer can ascend to Santa Cruz, in 

 the heart of Bolivia. Colonel Church, who sounded the 

 Mamore for 600 miles above the rapids in October (the 

 dry season), found nowhere in mid-channel less than fifteen 

 feet of water, an average current of two miles an hour, and 

 a width varying from six to twelve hundred feet. A rail- 



* There is, however, a dangerous point three days' steam from Sei-pa, called 

 Piedras de Uruas. But from January 1st to April 30th steamers of sixteen 

 feet draught can ascend to San Antonio. Exceptionally high floods occur on 

 the Upper Madeira every seventh yeai\ 



