of country from which a river receives its supply of water, by brooks and rivulets, is termed its basin, because a region generally bounded by a rim of high lands, beyond which the waters are drained off into another channel. The basin of a superior river includes those of all its tributary streams. It is sometimes the case, however, that the basins of rivers are not divided by any elevations, but pass into each other, a connection subsisting between their waters. This is the case with the hydro-graphical regions of the Amazon and Orinoco, the Cassiaquaire, a branch of the latter, joining the Rio Negro, an affluent of the former. The vague rumors that were at first afloat respecting this singular circumstance, were treated by most geographers with discredit, till Humboldt ascertained its reality, by proceeding from the Rio Negro to the Orinoco, along the natural canal of the Cassiaquaire. Rivers have a thousand points of similarity, and of discordance. Some exhibit an unbroken sheet of water through their whole course, while others are diversified by numerous islands. This peculiarly characterizes the vast streams of the American continent, and contributes greatly to their scenical effect, of which our illustration gives us an example, selected from the beautiful Susquehanna, the largest Atlantic river of the United States. The St. Lawrence, soon after issuing from the Lake Ontario, presents the most remarkable instance to be found of islands occurring in a river channel. It is here called the Lake of the Thousand Islands. The vast number implied in this name was considered a vague exaggeration, till the commissioners employed in fixing the boundary with the United States actually counted them, and found that they amounted to 1692. They are of every imaginable size, shape, and appearance; some barely visible, others covering fifteen acres; but in general their broken outline presents the most picturesque combinations of wood and rock. The navigator in steering through them sees an ever-changing scene, which reminds an elegant writer of the Happy Islands in the Vision of Mirza. Sometimes he is inclosed in a narrow channel; then he discovers before him twelve openings, like so many noble rivers; and soon after a spacious lake seems to surround him on every side. River-islands are due to original surface inequalities, but many are formed by the arrest and gradual accretion of the alluvial matter brought down by the waters. [Illustration: =The Susquehanna.=]