Peru to the mouth
of the Amazon.

Two new rivers were discovered by the Commission flowing into the
Pichis. One of them was named the Trinidad, from having been
discovered on Trinity Sunday, and the other was called Herrera-yacu,
after Major Ramon Herrera, of the Peruvian Army, who commanded the
escort of the Commission. The supplies of the expedition were running
too short to allow of any but a cursory examination of these two
rivers. The Trinidad, trending to the westward, can only be of value
as affording a water route to the plains lying between the Pichis and
the Ucayali, but it is possible that the Herrera-yacu may furnish a
nearer water route to Cerro de Pasco than any yet known.

Whilst the canoes of the Commission were descending the Pachitea, they
were attacked by the Cashibos, who assembled on the banks of the
river, and, waiting until the leading canoes had passed, let fly
flights of arrows at the canoe which brought up the rear. The Cashibos
were dispersed by a few rounds from the Remington rifles of the
Commission, and the explorers met with no further forcible opposition
on the way to the steamers awaiting them at the mouth of the Pachitea,
where they arrived after a canoe voyage of forty-one days, during
which many difficulties and some dangers were encountered and
overcome. Not a single person under Tucker's command was killed, or
died from sickness, during this expedition, and, singular to relate,
after all the hardships and exposure endured the explorers were in
much better health when they returned to their steamers than when they
left them at the beginning of the expedition.

On the 15th of July, 1873, the steamers _Tambo_ and _Mayro_,
comprising the exploring squadron, reached Iquitos after an absence of
three months and ten days. From the 15th of July to the 18th of
September the Hydrographical Commission was on shore at Iquitos,
employed making charts of the surveys of the late expedition, whilst
the steamers were being refitted for further service.

On the 18th of September the Commission again embarked and proceeded
to the mouth of the Yavari river, which forms the boundary between
Peru and Brazil. The greatest pains were taken to properly establish
this point. On a small island in the middle of the river, and very
near its confluence with the Amazon, many astronomical observations
were taken, resulting in giving the latitude 4 deg. 18' 45" south,
longitude 69 deg. 53' 10" west of Greenwi