Chap. II. 
TIDES. 
123 
creek became dry with the continued subsidence of the 
Cupari, the time of rising shifting a little from day to 
day. I pointed out the circumstance to Joao Aracii, 
who had not noticed it before (it was only his second 
year of residence in the locality), but agreed with me 
that it must be the " mare." Yes, the tide ! the throb 
of the great oceanic pulse felt in this remote corner, 530 
miles distant from the place where it first strikes the 
body of fresh water at the mouth of the Amazons. I 
hesitated at first at this conclusion, but on reflecting 
that the tide was known to be perceptible at Obydos, 
more than 400 miles from the sea ; that at high water 
in the dry season a large flood from the Amazons 
enters the mouth of the Tapajos, and that there is but 
a very small difference of level between that point and 
the Cupari, a fact shown by the absence of current in 
the dry season ; I could have no doubt that this con- 
clusion was a correct one. 
The fact of the tide being felt 530 miles up the Ama- 
zons, passing from the main stream to one of its afflu- 
ents 380 miles from its mouth, and thence to a branch 
in the third degree, is a proof of the extreme flatness of 
the land which forms the lower part of the Amazonian 
valley. This uniformity of level is shown also in the 
broad lake-like expanses of water formed near their 
mouths by the principal affluents which cross the valley 
to join the main river. 
August 21st — Joao Aracu consented to accompany 
me to the falls with one of his men, to hunt and fish 
for me. One of my objects was to obtain specimens of 
the hyacinthine macaw, whose range commences on all 
