78 THE AMAZON AND MADEIRA RIVERS. 
that, twelve years ago, a tat cow could he purchased at the Missions 
for throe pesos (ten shillings); whereas it noAV fetches about thrice 
that sum. Near the mouth of the Matucare, a small influent on the 
right, such a fresh breeze set in, inviting us to unfurl our sails, that 
simultaneously, on all the canoes of our little fleet, prejjarations were 
made to profit by it. Masts of every kind — ^lioth straight and crooked ; 
some vertical, others bending forward or backward — were set up ; auxl 
sails, of shapes certainly not to be found in nautical handbooks, 
Avere utilised for the occasion; not omitting hammocks and musqui- 
teiros; but our heavy boats glided along under them, nevertheless, 
with unwonted swiftness. We passed in this way the only little rapid 
of the Mamore, with a slope of 2 inches and a length of 660 feet, 
caused by a ridge of Pedra Canga stretching right across the river. 
As this Pedra Canga is situated (as on the Amazon) on soft, finely 
laminated clay, which is easily solved by water, the layer of not 
very hard sandstone loses its base and tumbles down in large frag- 
ments. This process of breaking off, and the consequent receding of 
the rapid, Avill go on imtil the whole bank is destroyed; when the 
river will quietly flow along in its widened and deepened bed, leaving 
only the rocks on both the shores as final memorials of the fonner 
obstruction. These signs being found on eight or ten places on the 
Mamore, I do not doubt that, ages ago, it had as many rapids thus 
levelled by the river itself in the coru-se of time. 
The Matuc.ar^ affords an easy road, at high water level, to the 
former Mission of Sao Joaquim on the Machupo ; the country being 
a dead flat for a considerable extent, and the little lake, whence 
rises Matucare, discharging itself on the opposite side, in the direction 
of the Machupo. 
In the dry months, the voyage between Exaltacion and Sao J oaquim 
must be made on foot, by barely accessible paths in the woods; and 
I cannot omit to mention here, in proof of the hard condition of 
]3olivian Indians, that two of them, cai-rj-ing seven or eight arrobas 
(about 240 pounds), were paid one peso (about four francs) for this 
trip, out of which they have to provide their OAvn food. In this 
five days’ march they have to cross A'ast swamps Avith their heavy 
loads, cruelly tormented by the mosquitos at night, and moreover, 
exposed to the attacks of wild Indians, Avho seem to hav'e taken up 
tlieir station in this Avilderness. In fiict, tlicy are no better off than 
