There is a fine tract of rich level land extending along the eastern shore of the Mississippi about eighty miles in length, and from three to six miles in width. It commences near New-Alton, and terminates a little below Kaskaskia. About half of its width bordering on the river, is covered with a heavy growth of timber; the remainder is a level prairie; and in the rear it is bordered by a stately bluff of limestone. It is undoubtedly the richest land in the world. Settlements have been made upon it to some extent, but it is not very healthy. It is called the American Bottom. A bottom very similar to this, either on one side or the other, marks the whole course of the Illinois river. More than five millions of acres have been surveyed, between the Mississippi and Illinois rivers, and assigned by Congress for military bounty lands. These lands embrace all the varieties of soil found in the State--rich bottoms, swamps, prairies, timbered lands, high bluffs and barrens. The northeast part of it is deemed the most pleasant and healthy. On Rock river, the Kaskaskia, Wabash, Fox, Du Page, Macoupin and Sangamon are large tracts of first rate land. And very similar to this, are Grand prairie, Mound prairie, the Marine Settlement prairie, and the one occupied by the New-England Christians. In the region of Sangamon river, nature has delighted to bring together her happiest combinations of landscape; being beautifully variegated with woodland and lawn, like sunshine and shade. It is generally a level country; the prairies are not too extensive, and timber abounds in sufficient quantity to support a dense population. In this beautiful section of the new world, more than two hundred families, from New-England, New-York and North Carolina, fixed their habitations before it was surveyed. The land is exceedingly rich and easily cultivated. It now constitutes a number of counties and is probably as thickly settled as any part of the State. The Sangamon itself is a fine boatable river, and has throughout its whole course, pure, transparent water and a sandy bottom. It enters the Illinois river on the easterly side, about one hundred and forty miles above its mouth. The Kaskaskia river has a long course in the central part of the State, and the lands upon its borders are happily diversified with hill, vale, prairie and forest. On its banks are Kaskaskia, the former seat of government, and Vandalia, the present metropolis.