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 the rising water soon floats the vessel off. Hence it is, of course, that the navigation of the Amazon is attended with much less difficulty when the waters of the river are rising than when they are falling. FUEL. Coal is not to be found on the Upper Amazon; the steamers burn wood, which is abundant, cheap and makes good fuel. Wood should be ordered in advance at certain points, but in case a steamer gives out of fuel all that has to be done is to haul in to the bank, send the crew on shore with axes, and cut as much wood as is required. DISCHARGING AND RECEIVING CARGO.