Edwardsville spectator. [volume] (Edwardsville, Ill.) 1819-1826, 1825-02-01

/ have guard lock at ), on the river Des
PLANES, and one or probably two for tle
feeding canal from the lake of the Saga
nashkee.
By the foa1rth route, we have the as
cent to the Chicago equal to 1871 #. II
in. 7--deductipg from this #. IN. 7,
the ascent from Cache island, as before
shewn, consequently, on this route, ma
king the same assumption for the incli-
nation Of the canal, as before, we shall
have l48 #. 5 in. OF lockage, which will
require
10 locks of f. in. lift each-and probably
s guard locks.
In this case, it is probable that all the
guard locks required will be those al
ready designated on the route between
Cache island aud Fox river, inclusive.
Should any others be required, they will
evidently be located as follows: one at
the head Of Chicago river, and one at the
south side OF the reservoir al Cache ISL
and.
BY the nth and last route considered,
the entire ascent, as before, is ST 1t. III
in. Z, which, snpposing The inclination OF
the canal as in the former cases, will
give lag #. 10 in. Of lockage, and re-
quire
1olocks off fl. 10 in. lift EACH
hdhering in this route to the suppo-
sition oil obtaining from Lake Michigan
The entire supply of water to be used. ii
is probable that all the guard locks re-
quired, will be one at the head of Chi
csgo river, and if required and found
practicable to construct, another in the
Ssganashkee.
In all the routes above suggested, the
horizontal plane of the lift locks are sup
posed to be the same, for example,
Length, IS feet,
Breadth, IL do. az each end,
having batter on each side of the lock
OF half an inch in each foot perpendicu
lar height: the horizontal section of Its
sides being extremely fat esliptical arch
cs nearly approximating right lines, the
chords being respectively 76 feet, aud
each t,eche one half Of an inch for each
perpdendlcular foot OF the height of the
lock. Such is the plan OF the princ-
pal locks on the New York Grand
Canal. This peculiar construction be-
ingadopted, without doubt, to give more
strength to the sides of the locks, and
thereby to enable them to more eiiec-
tuaily Sustain the lateral pressure o;
the adjoining earth. But on the suppo-
sinon Of cavities being left, OF subse-
i<sts IL
sorry, this precaution to acquire strength
and give stability TO the lock would alb
salutely weaken it, and leave us sides
more exposed to the pressure oil the wa.
ter in It's chamber, than would be eXpe-
rienced by having the walls Of the cham.
Der straight and perpendicular The de-
feet of the ellip,ical form and batter Of
| the sides of locks has been experienced
in the Canal OF Languedoc, and suisse
quently avoided in the straight and per-
| pendcular sides given to The chambers
of those in the Canal of Picardie, in that
OF Gravilincs, and in many others con-
slructed on the continent of Europe
Another and very important advantage
possessed by the locks with straigh, and
perpendicular sides, is, the additional "a.
cili,y and reduction of expense attending
their constructions consideration at all
| times, where absolute utility, instead Of
! ornament, is consulted, worthy the most
serious attention.
The next subject claiming inves,iga-
ton, is the manner in which convenient
and sure entrance may be had into Lake
Michigan. On this point there has been
considerable diversity Of opinion ex-
pressed by persons visiting the place
some of whom, on examination of the
sand bar formed by the operation of the
surf Of the Lake, in front of the mouth of
the Chicago river, have considered the
formation and continuance Of a navigable
inlet into the river, to be hopeless task,
the prevailing winds having a tendency
to accumulate sand on that shore; but
rejecting on the improvements, from
time to time, made in the harbor OF Dan.
kirk, as particular example, the reflect
ing mind will readily assent to the prac-
ticability of the achievement.
To ascertain the probable expense of
efecting this object, the undersigned
have sounded the Lake sufficiently far
from the shore to obtain depth OF feet
| Of water, which IS supposed to be suffi-
cient for any of the vessels navigating
the Lake. Influenced by the result of
these observations, the undersigned re-
commend to the consideration of the
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