"It is," Dr. Bronson answered, "and many of them are lost every year. But those engaged in navigating the river know when to expect the bore, and take precautions against it. They have esperas, or resting-places, where they are sheltered from its force, and wait until it has passed.
"The bore is not confined to the Amazon," continued the Doctor; "it is known in other rivers, especially in the Hoogly, below Calcutta, but the bore of the Amazon is undoubtedly the largest."
IN AN IGARIPÉ.
"Another curious feature of the Amazon," said Frank, resuming, "is the great number of lateral channels, which are technically called igaripés, or canoe-paths. Boats may go for hundreds of miles along the lower Amazon in the igaripés without once entering the main stream. They remind us of the bayous of the lower part of the Mississippi Valley."
"Don't forget," said Fred, "that the Amazon rises within sixty miles of the Pacific Ocean, and touches every country of South America except Chili and Patagonia. The Madeira rises close to the sources of the La Plata, while the Negro, the great northern tributary of the Amazon, is connected with the Orinoco by a navigable canal called the Cassiquari. The navigation of this network of waters is favored by nature; the current is eastward, while the trade wind blows west from the Atlantic, so that ships going either way have the stream or the wind to help them along."
"And another thing," said the Doctor, "that should be mentioned, is the annual rise and fall. There is a succession of freshets in the tributaries of the Amazon, so that the main stream can never run low. Most of its affluents are in the southern hemisphere, and consequently the river has its greatest flood when the sun is south of the equator. The rise is gradual, beginning in September or October, and increasing not more than one foot daily, and often less than that. The difference between the highest and lowest levels is about forty-five feet, and at the time of the flood vast areas of land are covered with water. Once in every six years the flood is greater than usual."
"The Amazon is too large to be content with one name," said Frank. "From its mouth to the junction with the Negro it is called the Amazon, or the Amazons; from the Negro to the Peruvian frontier it is the Solimoens; and the part in Peru is the Marañon. But these distinctions are passing away since the river was opened to universal navigation; the Solimoens is now generally called the Middle Amazon and the Marañon the Upper Amazon. Probably another twenty years will see the old names disappear altogether."
Manaos is on the Rio Negro, ten miles above the junction of the latter stream with the Amazon. Frank and Fred observed with interest the change from one river to the other, which was as marked as that from the Mississippi to the Missouri, near Alton, Illinois. The Amazon is yellow, while the Negro, as its name indicates, is black. For miles the line between the two waters is sharply defined; they hold apart from each other, as if unwilling to mingle, but the greater river at length absorbs the smaller, and henceforth, to the sea, the yellow color is retained.