only a small affair, 6 ft. deep, and 60 ft. wide on the surface; the locks were 110 ft. long and 18 ft. wide.  The summit level, which was only 8 ft. above the lake, was 21 miles in length.  This limited waterway remained in use for a number of years, until, in fact, the growth of Chicago rendered it impossible to allow the sewage to flow any longer into the lake.  In 1865 the State of Illinois sanctioned widening and lowering the canal so that it should flow by gravity from Lake Michigan.  The enlargement was completed in 1871, by the city of Chicago, and the sewage was then discharged toward the Illinois River.  But the flow was insufficient, and in 1881 the State called on the city to supplement the flow by pumping water into the canal.

[Illustration:  FIG. 1]

In 1884, engines delivering 60,000 gallons a minute were set to work and remedied the evil for a time, so far as the city of Chicago was concerned, but the large discharge of sewage through the sluggish current of the canal and into the Illinois River proved a serious and ever-increasing nuisance to the inhabitants in the adjoining districts.  To enlarge the existing canal, increase the volume and speed of its discharge, and to alter the levels, so that there shall be a relatively rapid stream flowing at all times from Lake Michigan, appears the only practical means of affording relief to the city, and immunity to other towns and villages lying along the route of the stream.

The physical nature of the country is well suited for carrying out such a project on a scale far larger than that required for sewage purposes, and works thus carried out would, to a small extent, restore the old water regime in this part of the continent.  Before the vast surface changes produced during the last glacial period, three of the great lakes—­Michigan, Huron and Superior—­discharged their waters southward into the Gulf of Mexico by a broad river.  The accumulation of glacial debris changed all this; the southern outlet was cut off, and a new one to the north was opened near where Detroit stands, making a channel to Lake Erie, which then became the outlet for the whole chain by way of Niagara.  A very slight change in levels would serve to restore the present regime.  Around Lake Michigan the land has been slightly raised, the summit above mean water level being only about 8 ft.  Thirty miles from the south shore the lake level is again reached at a point near Lockport (see Fig. 2); the fall then becomes more marked.  At Lake Joliet, 10 miles further, the fall is 77 ft.; and at La Salle, 100 miles from Chicago, the total fall reaches 146 feet.  At La Salle the Illinois River is met, and this stream, after a course of 225 miles, enters the Missouri.  In the whole distance the Illinois River has a fall of 29 ft.  “It has a sluggish current; an oozy bed and bars, formed chiefly by tributaries, with natural depths of 2 ft. to 4 ft.; banks half way to high waters, and low bottoms, one to six miles wide, bounded by terraces, overflowed during high water from 4 ft. to 12 ft. deep, and intersected in dry seasons by lake, bayou, lagoon, and marsh, the wreck of a mighty past.”