New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1876-09-16
HALLE1T'S POINT.

REMOVING HE'LL GATE INSTRUCTIONS.
CONVENIENT ExAaSAuONs-GEN. MENTIONS PLAN
AND IFS ExEcUnoN--PREsEST STATE or TIE
WORK.
Ualett's Reef, which has long been q source
OF danger to naygators OF Hell Gate, viii DO utterly
destroyed reef within the next few weeks ana ony
the debris which VIII result from its destruction VIII
have 10 be removed to Insure safe channel IL has
been estimated that sailing weasel out OF every
hfy that now attempts the passage meets with
acme Incident. Surveys az the channel and esti-
mates OF the cost OF removing the various rocks,
as well ~ Hallets Reef, have been made moro than
once nj tine Government expense. Something was done
toward improving the channel by NJ hailefer who be-
gan operations ia 1891, by Of fund Of $4,000
raised by subscription among the citizens OF this city
His method was surnce distinguishing charge down
against the rock and exploding itaud the results were
more or less favorable, according to the shape OF tue
rocks Those which Of conical or counnar shape
were easily shattered, while upon those Aa"ing nat
surface Of any the effect OF tue blasting was slight
IL OF any service When 1t Determined at last to re-
move these obstructons to navigation, without regard
t the cost the important question which puzzled the
minds Of engineers tine manner In which IL should
be done.
I'm 1866 Brevet MajOrGen John Newton Of the United
States engineers was ordered by the Engineering De
partuent To examine He'll Gate and make report en-
bracng plan and estimate OF cost for It's Improvement
The report submitted III Aoof' ihO
proposed by Gen Newton has gradually developed itself
INN the what is now known the drilling scow" This
method however was the Of several accidents
great number Of vessels having been thrown against tho
scow by the force OF the currents where II has been an
chored. During the operations at Pot Rock in Hell
Gate ON August until Dec. 2S, 1872, 16 vessels came
IN collision with it. Four of the vessels were
sunk and one OF them, which contained 200
tons of coal was carried by the rapidity of
the current under the scow, tearing ii from
Its moorings inhicting great injury upon Its ma
chnery IL was upon this scow, anchored at Hat
etts Point that the late accident occurred whereby
three men lost their lives. The scow Itself seems in-
dcstrucIibe Tor all tho collisions and even th expo-
sion have had no effect upon II beyond the SCATTERING of
one or two OF deck tmbcrs IL has the appearance oil
an ordinary scpw IL Is built of heavy tlmbers and Is
very compact In the center ia wcll-hoie 81 feet IN
diameter and inside of 1t Is dome 30 feet In diameter
connected with the by four chains. The
scow, with the dome drawn up and swung
by these chains Is anchored over the rock To
be operated upon, and the dome Is then lowered
until sufficiently Its surface. Adjustable legs are
then let down which are shortened heightened accord
ing 10 the surface Of the rock aud hold the dome In an
upright position Inside Of the dome-which If open Mt
top and bottom and supported by ills system OF tubes
81 In number, through which the drills rise ana iail'
When the drilling completed the scow is removed 10
safe distance and the holes filed with explosive ma
arc then exploded by electricity BY this plan the dep'h
~ water AT Coontes Reef been increased from 10 to
90 Eeot; ut Ways from II to 20 feet; Diamond ana
other reefs have boon partially removed
HALLETT's POINT REEF.
According to Gen. Nowtons statement "this reef Is In
shane an irregular seni-cpse ME longer axis which lies
next TO the shore being 720 feet In length, aud the
shorter sciniaxis projecting straight into the channel
about 800 feet The cubic contents above the depth OF
90 feet AZ mean low water amounted before any excava
tons were made to 81 600 cubic yards Besides tho rsk
of striking the reef produces edes on both sides OF
according TO the direction OF the tidal currents ana
much I'm the way of vessels coming down WIN the eOO Ia
the effort hug the shore and thus avoid being thrown
upon tie Middle Reef. 1t Is in the way OF large ana
small vessels equally, and Its removal an essential
element In the Improvement ol ~. .s vnanb b.
Tho prncipo Of tunneng In rocks under the water 1
been known aud carried out for number OF years.
When frat used the explosive material was placed upon
The floor OF the excavation Cen Newtons plan Includes
The nIercng of the roof OF the tunnel ana ts supporting
niars with holes aud placing the destructive material
In them In small clarges BY this means-the water
Ina wing beeu admitted the tunnels and by rs con-
iined condition acting lamp, or means on resist
ance 10 each separate charge-the vibration VIII DC
largely decreased and II Is thought that no oLner aa