THE UPPER UCAYALI. 213 



cade, was, by the barometer, nine hundred and four feet below it; thus 

 giving the river a fall of Si of a foot per mile. 



He says that if the navigation of the Ucayali is attempted, it would 

 be well to make a port at this point, and open a road thence to the 

 valley of Sta. Ana, in which Echarate is situated, and which is exceed- 

 ingly fertile, producing large quantities of Peruvian bark, with coca, 

 and many other tropical productions. 



M. Castelnau thinks that this last cascade is the first impassable 

 barrier to the navigation of the Ucayali upwards; but he found many 

 places below this where the river had but a depth of three feet, and 

 many, though unimportant, rapids. Indeed, two hundred and seventy 

 miles below this, he describes a strait, called the Vuelta del Diablo, as 

 a dangerous passage, blocked up by heavy trunks of trees, against 

 which the current dashes with great violence. 



At two hundred and sixteen miles below the cascade he passed 

 the mouth of the river Tambo, the confluence of which with the 

 Urubamba makes the Ucayali. 



Two hundred and fifty-two miles below the mouth of the Tambo he 

 passed the mouth of the Pachitea, which he describes as being about 

 the size of the Seine at Paris; and the Ucayali, after the junction of 

 this river, as like the Thames at London. 



Sarayacu is two hundred and ninety-seven miles below the mouth of 

 the Pachitea. 



From the Yuelta del Diablo to Sarayacu is four hundred and ninety- 

 five miles. From Sarayacu to the mouth of the Ucayali is two hun- 

 dred and seventy-five miles; so that w r e have an undoubtedly open 

 navigation on this river of seven hundred and seventy miles ; and, 

 taking M. Castelnau's opinion as correct, there are two hundred and 

 seventy miles more to the foot of the last cascade on the Urubamba; 

 making a total of one thousand and forty miles. Well, then, may he 

 call this stream the main trunk of the Amazon; for, taking my esti- 

 mate of the distance from the mouth of this river to the ocean, at two 

 thousand three hundred and twenty miles, we have an uninterrupted 

 navigation of three thousand three hundred and sixty miles, wdiich will 

 be found in no other direction. I estimate the distance from the Pongo 

 de Chasuta, the head of clear navigation on the Huallaga, to the sea, 

 at two thousand eight hundred and fifteen miles. 



An idea may be formed of the difficulties and dangers of passing the 

 rapids of these rivers from the following description, given by this 

 accomplished gentleman and clever writer : 



