New-York tribune., 1869-02-26
THE POLYTECHNIC SOCIETY.

The Polytechnic Society of the American
Institute met at Cooper Institute last night Prof Tman
In the chair The regular order OF business was suspendeu
10 give Mr. T. d. stetson opportunity to give an
account OF o recent visit to the Chicago tunnel that
gentleman being unable TO remain through the meeting
Mr. steson said that confusion had existed In re-
gard to the tunnel at Chicago There were two tunnels
In that city, One extended under the lake two miles and
was full of water Through this the city obtained pure
water from q point in tho lake beyond the
influence Of the sewerage ana bhh OF the
tended to talk about The other tunnel under the
Chicago River and practical success THIS was an
interesting topic that tunnel under the East River
is talked Of The Thames tunnel had been success to
certain extent Foot Passed a th5Gg pr Sarn
rageways in actual use under the south branch OF
eariares g actually drove through tunnel under nav
gable river. This tunnel at the crossing or washington
building drawbridge, such is found every other
street, crossing the river great deal OF shipPrhg
river was not deep-about /. feet at the point in
question. The depth OF the tunnel was lS feet
for foot passengers It was lighted throughout with gas
The width OF the river 20 feet The tunnel was not
constructed by tunneng in the ordinary meaning OF the
word Golfer dam was built so that one side of tho
river might be jumped at time that NAVIGATION @ nt might
ditch from the top, and then walled up and arehed over
dry by well sunk in the middle leading to sewer,
which conveyed the water to one side OF the ryer
the sides are Bituminous cement top Of the
| brick concrete that aud hagstone Btill above,
1 forming the bed OF the river. The top OF the
tunnel is nearly on level with the bottom OF the river
In regard to tunDeng the East River from NewYork 20
Brooklyn, people had generally an Idea that was to be
done by laying immense iron tube on the bottom In
tunneng In the ordinary way under this river two very
unmanageable materials would be found IN the way
qucksand and rock This very different from the
had simply cut through stiff blue clay. There
similar bed OF clay under Chicago Tho speaker enume-
rated the usual difficulties met with in tunnelng. Tho
Chicago Tunnel practical IL 220 feet
across the river, and the entire length OF the tun-
mel, to secure proper, grade, was lCco
| different points. The specifications called
ventilation. but the current Of air through the tunnel
was quite sufficient in fact complained OF as being
too strong The grade foot IN Is. The width OF
the tunnel about 80 feet The next business In order
being the exhibition OF new Inventions Mr. Edmund Fer
guson presented model OF section for iron tunnel
TO be laid on the bottom OF the East River The shape
iron The shell is double, and made OF iron plates firmly
riyeted and waertight These sections arc TO DO laid
| down at q time, and the connection made under
water Each end Of the section IL closed until the
connection Is made with the preceding sec
1 ton when the partition is removed, and so on
the river Several gentlemen spoke highly Of the
apparant feasibility Of the plan. Mr. Ferguson estimates
at s2,50o0Oo. Mr. B. L. Lomathe presented O plan for
combined suspension and truss-bridge.
The Society then took up the regular subject OF the
evening" Light and Colors." Dr. Vanderwey eyde deliv
cred entertaining lecture the Solar Spectrum and
the unduating theory OF light, illustrating by diagrams
and paintings the division Of light with the coors
and into the chemica and caloric rays He also spoke
presence and character Of the different metals by
of light.