navigation of the Upper Amazon that
these notes will treat.

RISE AND FALL OF THE RIVER.

The waters of the Upper Amazon and its tributaries begins to rise
annually in October, remains stationary for a short time in December,
then continues to rise until May, when it commences to fall. November,
December, January, February, March and April are considered the
months of high water, and June, July, August and September comprise
the low-water season. October and May are sometimes months of high and
sometimes of low water.

DEPTH OF WATER.

During the season of low water a minimum depth of twenty-four feet is
found in the channel of the Upper Amazon, from the Brazilian frontier
to the mouth of the Ucayali river at Nanta, eighteen feet from the
mouth of the Ucayali to the mouth of the Huallaga river, and twelve
feet from the mouth of the Huallaga to Borja, where further navigation
is rendered impracticable by the rapids and falls of the pongo de
Manseriche.

CURRENT.

From the Brazilian frontier to the mouth of the Ucayali river the
current of the Amazon is three miles per hour; from the mouth of the
Ucayali to the mouth of the Potro river three and one-fourth miles per
hour; from the mouth of the Potro to the mouth of the Morona river
three and a-half miles per hour; and from the mouth of the Morona to
Borja, at the head of steamer navigation, the current is three and
three-fourths miles per hour. This is the usual and average current to
be met with, but it increases or diminishes with the rise and fall of
the river and, also, with the narrowing or broadening of the channel.

PILOTS.

In order to prevent running upon sand-bars, which are constantly
forming and shifting and frequently changing the bed of the channel,
the services of experienced pilots are indispensable to the safe
navigation of the Upper Amazon and its tributaries. It is not
difficult to obtain such pilots, and they are frequently expert
hunters and fishermen as well as pilots.

BEST TIME FOR NAVIGATING THE RIVER.

When a steamer on the Upper Amazon runs aground, it is almost always
in consequence either of the ignorance of the pilot or of the
unskillful handling of the vessel. To get aground when the water is
falling endangers the detention of the vessel until she is floated off
by the next rise of the river, which may not occur for months; getting
aground when the water is rising usually necessitates a delay of only
a few hours, as