88 NOTES OF A BOTANIST 
stream be swollen it is quite impassable, and 
travellers have to wait till it abates. The whole 
number of these crossings is twelve, and after 
leaving it a tributary stream of scarcely less size 
has to be crossed thrice in ten minutes. 
Many attempts have been made to find a way 
which shall avoid the gorge of the Cachi-yacu, but 
hitherto without success. Beyond this there is a 
long painful ascent to a spring of clear water called 
Potrero, where the traveller begins to emerge on 
the grassy plateaux and declivities of the Campana. 
In imitation of the tambos or houses of rest and 
refreshment placed by the Incas along their great 
roads, the modern Peruvians have erected sleeping- 
places wherever the pueblos are at too great a 
distance to be reached in one day. To these also 
they give the name of tambos, but they are as 
inferior to the ancient ones as are the modern roads 
to the solid structures of the Incas. They consist 
of a roof supported on four bare poles, without 
walls, but when large and well-made such shelters 
answer their purpose tolerably well. Of course 
they have no permanent occupants, and the only 
thing a traveller can calculate on finding when he 
reaches a tambo is fire, which is rarely allowed to 
become extinguished, as it is the custom for those 
who have last occupied it to leave their fire well 
heaped up with rotten logs. A slight channel 
is made round the tambo to carry off rain-water, 
and the soil taken out serves to heighten the floor- 
ing, which, being spread with palm-leaves or with 
fern, the traveller extends thereon his mattress or. 
his blanket, and wrapped up in his poncho and 
another blanket, may calculate on passing the night 
