h that in many places little islands were completely submerged,
and the current raced among the trunks of the green trees. At one
o'clock we came to the mouth of the Castanho proper, and in sight of
the tent of Lieutenant Pyrineus, with the flags of the United States
and Brazil flying before it; and, with rifles firing from the canoes
and the shore, we moored at the landing of the neat, soldierly, well
kept camp. The upper Aripuanan, a river of substantially the same
volume as the Castanho, but broader at this point, and probably of
less length, here joined the Castanho from the east, and the two
together formed what the rubbermen called the lower Aripuanan. The
mouth of this was indicated, and sometimes named, on the maps, but
only as a small and unimportant stream.

We had been two months in the canoes; from the 27th of February to the
26th of April. We had gone over 750 kilometres. The river from its
source, near the thirteenth degree, to where it became navigable and
we entered it, had a course of some 200 kilometres--probably more,
perhaps 300 kilometres. Therefore we had now put on the map a river
nearly 1,000 kilometres in length of which the existence was not
merely unknown but impossible if the standard maps were correct. But
this was not all. It seemed that this river of 1,000 kilometres in
length was really the true upper course of the Aripuanan proper, in
which case the total length was nearly 1,500 kilometres. Pyrineus had
been waiting for us over a month, at the junction of what the
rubbermen called the Castanho and of what they called the upper
Aripuanan. (He had no idea as to which stream we would appear upon, or
whether we would appear upon either.) On March 26 he had measured the
volume of the two, and found that the Castanho, although the narrower,
was the deeper and swifter, and that in volume it surpassed the other
by 84 cubic metres a second. Since then the Castanho had fallen; our
measurements showed it to be slightly smaller than the other; the
volume of the river after the junction was about 4,500 cubic metres a
second. This was in 7 degrees 34 minutes.

We were glad indeed to see Pyrineus and be at his attractive camp. We
were only four hours above the little river hamlet of Sao Joao, a port
of call for rubber-steamers, from which the larger ones go to Manaos
in two days. These steamers mostly belong to Senhor Caripe. From
Pyrineus we learned that Lauriado and Fiala had reached Manaos on
Marc