ACROSS UNKNOWN SOUTH AMERICA 
“Hark!” said the German to me, “do you hear 
them? ” 
I listened attentively. Far, far down the river a faint 
chorus of voices could just be heard — intermittent 
sounds of “ hua . . . hua . . . hua . . . hua.” In the 
stillness of the night the sound could be distinguished 
clearly. It went on until sunrise, when it gradually 
died out. 
There was a big lagoon to the west of Porto Velho, 
formed by the river at high water. The lagoon dried up 
during the dry season. It was separated from the river 
only by a narrow tongue of land, eighty feet high. 
I took careful and repeated observations for latitude, 
longitude, and altitude, the latter by a boiling-point 
thermometer, from our point of departure at the head¬ 
waters of the Arinos River. The elevation of the river 
was there 1,200 feet by aneroid, 1,271 feet by the 
hypsometrical apparatus. The latitude was 14° 2'.2 
south; the longitude 56° 17' west of Greenwich. 
We were having beautiful, clear skies. Only on July 
fourth at sunset a solitary streak of mist extended to the 
summit of the sky. 
I had two plans in my mind when I decided to descend 
the Arinos River. One was to abandon that river at the 
point where it met the Juruena River and strike across 
country westward until the Madeira-Mamori Railway 
was met. The other plan, even more difficult, was to con¬ 
tinue down the river as far as its junction with the Tres 
Barras, from which place I would strike across the virgin 
forest as far as the Madeira River. I had not the faintest 
idea how I could realize either plan with the ridiculously 
meagre resources at my disposal. I had enough money, 
but unfortunately that was one of the few spots on 
earth where money was of little use. Again I trusted 
in Providence to come to our help. Both plans 
involved thousands of kilometres of navigation of a 
12 
