One of the gigantic public improvements of Chicago is that for supplying the city with water. Owing to the fact that the water in the lake, near the shore, was polluted by filth from the river, in 1865 a tunnel was cut under the lake, extending a distance of two miles from the shore. This tunnel is thirty-five feet below the bed of the lake. This work is regarded as an example of great engineering skill, and has proved to be successful. The contract price for this work was $315,139. Another great work is the tunnel under the Chicago river at Washington street, cut for the purpose of dispensing with the bridge over the river, and to obviate the necessity of the public waiting for vessels to pass. The contract price for this great work was $200,000.

There are other great public improvements of the city, which with her railroads leading out in all directions, her immense lake shipping trade, and her population of nearly half a million people, show the greatness that Chicago has attained, all within so short a time. As she has been great in her prosperity, so also has she been great in her calamities. On the 8th and 9th of Oc tober, 1871, this city was the scene of one of the greatest conflagrations known in the annals of the world-greater than that of London in 1666, when thirteen thousand buildings were burned. In Chicago twenty thou sand buildings were swept away by the devouring element, with miles of magnificent business blocks, palatial residences, and costly ornamentations -all covering an area of over five thousand acres! In all that part of the city between Harrison street and the Chicago river, and on the North Side for nearly four miles to Lincoln Park, there was nothing to be seen but the ruins of a city that had suddenly gone down at the merciless bidding of the fire-fiend. It was a scene of desolation and ruin, and its announcement at the time thrilled a sympathetic chord which vibrated throughout the whole civilized world. Like the fabled Phoenix, Chicago rose again from her own ashes, but grander and more magnificent than she was before. Chicago is now, and has for some years been, the greatest pork packing and grain shipping market of the world. Her commerce is of immense proportions and reaches to all lands where American trade is known. She is the commercial metropolis of the great Northwest, and the States of Illinois, Iowa, Nebraska, Wisconsin and Minnesota, pour their tributes of wealth over thousands of miles of railroads into her lap.

HISTORY OF IOWA.

DESCRIPTIVE AND GEOGRAPHICAL SKETCH.

Extent Surface-Rivers-Lakes-Spirit Lake-Lake Okoboji-Clear Lake-Timber-Climate Prairies-Soils.

Extent.-Iowa is about three hundred miles in length, east and west, and a little over two hundred miles in breadth, north and south; having nearly the figure of a rectangular parallelogram. Its northern boundary is the parallel of 43 degrees 30 minutes, separating it from the State of Minnesota. Its southern limit is nearly on the line of 40 degrees 31 minutes from the point where this parallel crosses the Des Moines river, westward. From this point to the southeast corner of the State, a distance of about thirty miles, the Des Moines river forms the boundary line between Iowa and Missouri. The two great rivers of the North American Continent form the east and west boundaries, except that portion of the western boundary adjoining the Territory of Dakota. The Big Sioux river from its mouth, two miles above Sioux City, forms the western boundary up to the point where it intersects the parallel of 43 degrees 30 minutes. These limits embrace an area of 55,045 square miles; or, 35,228,800 acres. When it is understood that all this vast extent of surface, except that which is occupied by the rivers, and the lakes and peat beds of the northern counties, is susceptible of the highest cultivation, some idea may be formed of the immense agricultural reSources of the State. Iowa is nearly as large as England, and twice as large as Scotland; but when we consider the relative area of surface which may be made to yield to the wants of man, those countries of the Old World will bear no comparison with Iowa.

Surface. The surface of the State is remarkably uniform, rising to nearly the same general altitude. There are no mountains, and yet but little of the surface is level or flat. The whole State presents a succession of gentle elevations and depressions, with some bold and picturesque bluffs along the principal streams. The western portion of the State is generally more elevated than the eastern, the northwestern part being the highest. Nature could not have provided a more perfect system of drainage, and at the same time leave the country so completely adapted to all the purposes of agriculture. Looking at the map of Iowa, we see two systems of streams or rivers running nearly at right angles with each other. The streams which discharge their waters into the Mississippi flow from the northwest to the southeast, while those of the other system flow towards the southwest, and empty into the Missouri. The former drain about three-fourths of the State, and the latter the remaining one-fourth. The water-shed dividing the two

systems of streams, represents the highest portions of the State, and gradually descends as you follow its course from northwest to southeast. Lowwater mark in the Missouri river at Council Bluffs is about 425 feet above low-water mark in the Mississippi at Davenport. At the crossing of the summit, or water-shed, 245 miles west of Davenport, the elevation is about 960 feet above the Mississippi. The Des Moines river, at the city of Des Moines, has an elevation of 227 feet above the Mississippi at Davenport, and is 198 feet lower than the Missouri at Council Bluffs. The elevation of the eastern border of the State at McGregor is about 624 feet above the level of the sea, while the highest elevation in the northwest portion of the State is 1,400 feet above the level of the sea. In addition to the grand water-shed mentioned above, as dividing the waters of the Mississippi and Missouri, there are between the principal streams, elevations commonly called "divides," which are drained by numerous streams of a smaller size tributary to the rivers. The valleys along the streams have a deep, rich soil, but are scarcely more fertile than many portions of those undulating prairie “divides."

Rivers. As stated above, the rivers of Iowa are divided into two systems, or classes-those flowing into the Mississippi, and those flowing into the Missouri. The Mississippi river, the largest on the continent, and one of the largest in the world, washes the entire eastern border of the State, and is most of the year navigable for a large class of steamers. The only serious obstruction to steamers of the largest size, are what are known as the Lower Rapids, just above the mouth of the Des Moines. The government of the United States has constructed a canal, or channel, around these rapids on the Iowa side of the river, a work which will prove of immense advantage to the commerce of Iowa for all time to come. The principal rivers which flow through the interior of the State, east of the water-shed, are the Des Moines, Skunk, Iowa, Wapsipinicon, Maquoketa, Turkey, and Upper Iowa. One of the largest rivers in the State is Red Cedar, which rises in Minnesota, and flowing in a southeasterly direction, joins its waters with Iowa river in Louisa county, only about thirty miles from its mouth, that portion below the junction retaining the name of Iowa river, although above the junction it is really the smaller stream.

The Des Moines is the largest interior river of the State, and rises in a group or chain of lakes in Minnesota, not far from the Iowa border. It really has its source in two principal branches, called East and West Des Moines, which, after flowing about seventy miles through the northern portion of the State, converge to their junction in the southern part of Humboldt county. The Des Moines receives a number of large tributaries, among which are Raccoon and Three Rivers (North, South and Middle) on the west, and Boone river on the east. Raccoon (or 'Coon) rises in the vicinity of Storm Lake in Buena Vista county, and after receiving several tributaries, discharges its waters into the Des Moines river, within the limits of the city of Des Moines. This stream affords many excellent mill privileges, some of which have been improved. The Des Moines flows from northwest to southeast, not less than three hundred miles through Iowa, and drains over ten thousand square miles of territory. At an early day, steamboats, at certain seasons of the year, navigated this river as far up as the "Raccoon Forks," and a large grant of land was made by Congress to the State for the purpose of improving its navigation. The land was subsequently diverted to the construction of the Des Moines Valley Railroad.