New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1873-07-19

the water inc Opposite VI
channels the removal Of Flood Rock and tho accom-
panying reefs was TO be till the other improve
ments had been completed Accordingly for the pres
ent Haetts Point was to DO the chief seat Of active
measures.
The plan for removing the reef was most novel and
yet most simple. A cofter-dam was TO be built around
that part Of rock which was just above water so
that the waves might DO kept from overlooking the rock
and interfering with che work. Within this dam o
uolygona excavation was then TO DO made, having q
general length Of about 70 feet and a~general
brSssath of Sboutao feet. with depth of 20 feet
80 below low u landward face was 70 coincide
with tho proposed water,liSS. q that &ss
would also be In part removal Of the From
tho bottom Of this great pit 10 tuhes were TO run out
like 80 many extended hRgers those nearest tho land
ward face OF the pit running, out parallel with the
face Of the pit and the taking between these
two extremes The tunnels having been extended several
hundred feet galleries we're TO be cut between them.
that rock and tho above 1t would be really left
standing on large number Of rock pillars. These pill
lars were then 10 be reduced 10 small size would
la consistent with strength, when they were to DO
drilled into and supplied with heavy charges OF nitro
gycerne. Charges OF the samo material were to be
placed also at the various points In tho roof OF the con-
nected eaverns and the several charges were To DO
united by wires Everything being ready for the OK.
poson the was 20 pc let into the cayerns and the
ehre nea WIN m m 30 bs 'Da nra .ns
The charges then to be exploded aneously
y.
ing three ceres would fan In ana DO broken up. much OF
10 sinking to depth sufficient 70 be out Of the way and
tho rest being In loose fragments, which could be-
dredged out
The inst Government assistance came in two success
sive appropriations. and amounted TO 100000 and tho
appropriations for the two Years since have averaged
sET 900 q year. The preliminary work was begun IN
about Suy 1862 and the excavation OF the great Dit
begun In October OF the same year This completed
bg tho Summer OF 1870. when the tunnehng was begun
The several Tunnels or headings" were numbered and
namod for convenience In working as follows First.
Faragut; Second, Madison; third. Humphrey; four,
Hoffman, ave. Sherman six Jefferson; seven, Grant
eight Mcclellan; ninth, Franklin tenth, Jackson. In
order 70 determine how 10 the channel bottom tho
roofs OF the tunnels could be cut away succeon OF
borngs from made that an accurate profile
OF the channel bottom was obtained BY using this as
guide the depth and hight OF e several tunnels could
be calculated, so as " be a. little below the channel
bottom possible, consistent with safety. In OF
the earlier tunnels this precapton bad wholly
In part neglected and serious was caused through
cutting roof too high Undor present plan about
ten feet OF lett between the tunnel roof and the
ehannel bottom The gness OF the formation 10 similar
70 that which aboands n the upper part OF the city but
difficult than would oterwise be and yet renders the
work much safer. Another dncuty Is fact that the
slratneatOn Is perpendicular. 80 that thoro are moro
seams through which the water trIeslch than would