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 Aracu, 

 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 21s£. — 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 



