The New York herald., 1876-09-16

patton tho glory that would accrue to himself and
his friend Fox from the success Of the great work
rHB THAMES TUNNEL
Brunei unhcsitatiugy grappled with mo problem OF
tunnelling under tho River Thames and solved 10
triumphantly in the face OF In ditculties and
inoxperience such undertakings. The line extended
from Rotberhhe 10 Mapping, distance OF about 200
feet passed through horizontal straa which, from
the fact tha. they Immediately undsrlny the river
were subjecs variations OF pressure created
by the tidal movements Tho work com
menced in 1925 and after overcoming many
difficulties and the effect OF several casualties was sue
cessfully completed in ls4s. Although until re-
Gently the Thames tunnel could not be classed ns
work OF great utility still the experience gained in It's
construction has mainly contributed the success OF
other works OF the character, and AZ great ex-
pertinent in subaqueous tunneling It must bo regarded
OF the most important undertakings OF the age
CORNISH MINES
Although prosecuted in tho ordinary work Of min
ing tho great submarine workings Of the Cornish
mines, which extend for considerable distances under
the must be regarded among tho most splendid
achieve Of modern engineering Far beneath the
rolling billows OF the Irish Sea- undisturbed by the
bowling storms that lash this n-bound coast with in
describablo fury and buried lar below the ocean
graves OF the shipwrecked sailors the miner
pick in hand, delves among the mineral treas
that have lain for myriads Of ages In the
bowels Of the earth and sends them the upper world
to play their part in the various branches OF human
industry The ocean Itself has thus proved to be All
insufficient barrier the aegressveness Of wealth
seeking man, and the success which has attended his
efforts under such extraordinary opposing conditions
encourages us IN the belief that but opening the
treasury OF nature and that all her wonderful wealth
is as yet comparatively untouched. These submarine
excavations also show the feasibility OF similar works
conducted on the grandest scale, and must regard
among the possibilities OF the future grand system
OF subaqueous communication between countries now
separated by considerable expanses Of water.
TIE TUNNEL MICHIGAN CHICAGO.
A smaey but less remarkable feat Of subaqueous
tunnelIing has been accomplished by American engi-
the construction OF the lake supply tunnel OF
the Chicago watcrworks. This work Is perfectly
unique, and its prosecution surrounded with dl-
cues that have not been met any preceding work.
The object being to introduce supply OF pure water
from Lako Michigan into the city OF Chicago from a
part Of the lake which unpouted by the drainage
OF such large city, became necessary to tunnel out
the bed OF the lako distance of miles
and connect tho subaqueous aqusduct with water
erected in the lake, from which the pure ele-
ment would flow into the conduit and so TO the
city. Such was the plan and 20 has been
executed, and Chicago is supplied with
covers Of %, 400 square miles Here We have
another example OF in subaqueous tunnslling
which challenges the admiration OF the world and sets
men thinking how the same results be produced
elsewhere. There scarcely limit to be placed To tho
engineering possibilities of the coming century when
We come to consider strides that have made
this Tho data and experience gathered in the
ecuon OF the great works have barely mentioned
sufficient to warrant any project like that Of the
Channel Tunnel or the railroad subway under the
Hudson River. We see no reason why tho Niagara
River cannot be tunnecd fow miles above the Falls,
for it will probably take many centuries before the
great river eat its way backward such distance,
and tho meantime science viii have provided
simpler of communication across tho foaming
waters OF the UpperSt Lawrence
The application of the principles Of subaqueous tun
neng to the removal OF rocks that obstruct channels
and render navigation dangerous in any harbor brings
us to the review Of the recent
BLOSSOM
in San Francisco Bay, California, and other similar OBJ
structions our own harbor; brings US to tho con-
sideration of another branch of subaqueous mining
which has assumed enormous Importance In the work
OF clearing harbors from dangerous rocks reefs
and other dangers navigation. Tho operations
cuted in the removal OF the Blossom Rock tho
FIRST trials OF the system OF internal working
distinct from the ordinary or external plan which had
hitherto been followed in such II must be re-
garded the pioneer work of kind, and has been
attended with the fullest measure OF success
According TO the accounts given Of this undertaking
by engaged in the mining operations the top the
rock about I've feet below the level Of low water
mean tide, ana the depth OF twenty -four feet
presented measuring lo5 feet long by los foct
wide, the shape being ehpticaL The estimated cubic
contents tho within the above lines measure
mcnt about 5000 cubic yards and the geological
character OF the rock that OF metamorphc sand.
stone in irregular strata This term metamorphic
when applied In geological sense, indicates that the
formation originally Of the aqueous class, but by
the subsequent action OF subtcrranean heat became
changed semi-igneons state, in which tho origi.
nal stratncation preserved but the constituent par
clcs have assumed variety OF crystalline forms sucn
as those presented by s,atuary marble.
OF INTERNAL EXCAVATION
The survey Of tho rock was made by Lieutenant
Colonel Williamson, OF the Engineer corps United
States Army, to whom General Alexander, OF the same
corps proposed plan for its removal by blasting In
1865 which embraced tho general features Of the plan
finally adopted and carried This latter the
sinking OF shalt through the centre OF the rock from
space its summit enclosed by a water tght Golfer
DAM and this vertical excavation reached the
required depth below the level the OF
rock was be chambered out by excavation until
there only remained the thin shell, which retained OF
course, the original outward form Of tho until
was finally destroyed by great explosion OF giant
powder enclosed In thiriy-eght ale casks and
old iron tanks the whole charge representing 43 900
pounds OF powder The WORK was executed by the n.
gEcer and contractor Mr. A. W. Won Schmidt under the
inspection OF Lieutenant W. H. Heucr OF the Corps
Engineers, who Is now captain and has been for
q long time in charge OF tho operations
at He'll Gate New York Harbor The only
important change introduced by Mr. Won Schmidt in
carrying out the original plan proposed by General
Alexander the substitution OF telescope shaped
iron shaft Of which the sections, decreasing in dame
tor with the depth, slid downward one inside the
other, until tho roof level Of the internal excavation
WAS reached