abounds in the forests of the Upper Amazon, and the gathering of the
gum is a profitable industry. Specimens of gold have been obtained
from the natives about the pongo de Manseriche, and rich deposits of
the precious metal will without doubt be discovered at some future
time, but no search even can be made for it until the fierce and cruel
savages, who have undisputed possession of the country beyond Borja,
shall have been subdued.

MOUTH OF THE YAVARI RIVER.

Commencing at the Yavari river, which forms the boundary between Peru
and Brazil on the south side of the Amazon river, and following the
Upper Amazon and its principal tributaries up to the head of
navigation, the first place to be noted is the mouth of the Yavari
river:[2] Latitude 4 deg. 18' 45" south; longitude, 69 deg. 53' 10"
west of Greenwich; magnetic variation, 5 deg. 38' 54" east;
thermometer (Fahrenheit), 76 deg.; elevation above sea-level, 266
feet; distance from the Atlantic ocean, following the course of the
river, 1811 miles; current, in the Amazon, 4-1/2 miles per hour; width
of the Yavari river at its mouth, 500 yards; width of the Amazon, 1200
yards; depth of water in the channel of the Amazon, 36 feet. As the
Yavari river marks the boundary between Peru and Brazil on the south
side of the Amazon, special pains were taken to ascertain correctly
the latitude and longitude of its mouth; the observations for the
latitude and longitude were taken on a small islet, probably
overflowed at high water, in the middle of the lower mouth of the
river.

It was said in Iquitos that, in 1874, Captain Guillermo Black,
President of the Peruvian Boundary Commission, ascended the Yavari in
a small steamer a distance of 500 miles from its mouth, and 300 miles
farther in canoes to a point where there was barely two feet of water
in the channel, at which point the latitude was determined to be 7
deg. 1' 22" south, and the longitude 74 deg. 8' 25" west of Greenwich;
elevation above the sea-level, 800 feet.

TABATINGA (BRAZIL).

Distance from the Atlantic, 1825 miles; current, 4-1/2 miles per hour;
depth of water, 36 feet; width of river, 800 yards.

Tabatinga is the Brazilian frontier post on the north side of the
Amazon. Captain Azevedo, of the Brazilian Navy, gives the latitude of
this place as 4 deg. 14' 30" south; longitude, 70 deg. 2' 24" west of
Greenwich; magnetic variation, 6 deg. 35' 10" east.

LETITIA.

Latitude, 4 deg. 10' 57" south; longi