was, in fact, considered of sufficient
importance to call for legislation as early as 1822, in which year an
act was passed authorizing the construction of a canal having this
object. It was not commenced, however, till 1836, and was opened to
navigation in the spring of 1848. This canal extended from Chicago to
La Salle, a distance of 971/4 miles, and it had a fall of 146 ft. to low
water in the Illinois River (see Fig. 1). It was 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 th