Year: 1875

U.SA.


SRI havo tho honor to submit the following report
OF operations at Haetts Point for the fiscal year end
ing June so 1873. The work Of excavatng rock was
resumed during the last days of July 1874 and oon-
tinued almost without interruption during the re-
mainder Of the year. We only lost one work.
ing day since commencing operations for the
season. occasioned by the freezing Of the contents OF
our air and water pipes We therefore had eleven
consecutive months OF successful work, and during
this time blasted and placed the dumps l3 s3S cubic
Yards OF rock and made Gas feet OF progress In the
various tunnels. The headings and galleries are now
completed to the limit designed by you that to say
they carried out TO where the depth of water
head at mean low tide is twentysx feet The columns
of rock Q70 In numberl which support the roof have
been materially reduced tn size, and such portions of
the roof az unusually thick were trimmed down
as much as safety would permit In many places the
roof yet exceeds twenty feet In thickness but at these
localities the rock is OF so unstable character as not
to warrant any further reduction. The supporting
columns vary height from eight TO twenty-five feet
and average about ten feet in thickness The excava
tion being finished, we are at present engaged
in perforatng the roof aud piers with drill
holes varying from two to throe inches IN dahtef and
averaging about nine feet IN length the holes from
six feet apart and intended to receive tho
final charge Of explosive compound with which the
mine is be exploded The size Of the holes their d.
and distances apart vary with tho character Of
the rock, with the view 70 make the charge proportion
to the quantity Of rock necessary to be broken IL
probable that about 900 holes viii be required the
drilling of which at the present rate OF progress will
consume about year time. This tmo can, and ought
10 be- reduced nearly netnird by running three shifts
or drills instead Of two shifts at present The leak
age OF water into our work has increased from about
800 gallons minute TO little over 800 gallons
stoned by the numerous roof holes already drilled,
which tapped IN the rock through which water
flowed. Many Of these holes are being temporarily
plugged, which will nearly bring back the leakage 10
its former imits


Tho outside gallery and No. heading have been
deepened TO concentrate all the leakage and
cause dow the shaft end Of this heading, where
the pumps are placed, This together with the placing
OF boiler alongside the pump, has reduced the cost or
pumping TO minimum. on account OF the bad wen,
water obtained the works. which encrsted az well
as cOrroded boilers, a lead pipe lone and hall
inches interior diameter laid across the bottom OF
tho East River convey Croton here for steam
purposes. II served ts purpose well until midwinter,
when the intense cold froze ts contents, which re-
maned so for nearly three months Upon picking the
pipe up found that In depth of ninety feet
OF wster II was frozen solid whore the pipe came
above the surface. The surface tempera-
ture Of the salt water which surrounded
the pipe was % deg Fahrenheit The pipe was
several times broken BY vessels dragging their anchors
over IL hut vas auickly raIaired- During the year