The New York herald., 1870-02-10
SURFACE BLASTING.
mother Blow a. He'll Gate Operations.

6VhFACE O4AOAAN0'
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Auothcr Blow Mt He'll Gate operations
To THE EDITOR OF THE HERALD-
Ae supplementary to the historical resume OF tho
work OF surveying and removing the Hell Gate OBJ
strncrlons contained In the HERALD OF sunday, the
3oth ult, few facts relating TO surface blasting
taken from other sources than the Hell Gate opera
lions may be OF service TO the public III assisting 10
a correct opinion OF that mode OF removing rocks
under water. The supporters OF Mr.. Maileiert have
been SO persistent IN asserting his claims, ana 80
ready to leave the impression tnat the engineer of-
GERS In charge OF the work at Hell Gate are pre-
iudced against fim, taat portion OF the public
unacauainted with the facts, has been quite ready
to believe that surface blasting Ia his hands was all
that was claimed for IT, and that Mr.. Maiiiefert
the vicum OF the professional hauteur OF tho engi-
neer corps.
The following facts bearing on the subject are
taken from the report OF the Secretary OF War for
the year 1868, ana contained The report OF the
officer having IN charge the removal OF Middle Rock
New Haven narbor. lie says:-
The depth of water this previous commencing
operations was nine feet at low water From the report
%S M ns & % & rso I" this
the depth OF feet at low water for the amount OF
charges Of powder upon Il Mr. Maisisrt reporsa
b 70 effect the reduction for the sum tor aha @
rock 10 he level o M iect for Of the sppropria
Hn Msr n Sy M he
that her effect was much ess ,han ne naa me
to me- confident after Investigating the matter, that
them which would result in removing portion
Of the rock and that ihs amount available would suffice to
mark which was the depth required by the second contract
VIZ sas sG
water for $Sdou to work by the day and accom-
made an srranssaen. with Mr. Town.end eighty
to the as Of sepemser 1857 total Of
days. the total expended being 1850 The rock
place sixteen e The feet NOR. than was
offered to be done for Ssuo and one and halt feet more
Mailleiert for $4,000
Here Is proof conclusive as to the merits Of sur
face blasting compared with the method OF drilling
even Its primitive and simplest form employed
on Middle Rock. When we add to this fact that no
single rock OF the large number operated upon by
Mr.. Nal letert has yet anywhere been removed to q
given depth Of twenty-five feet, or any other depth
required by contract and to the other accumulated
evidence right on the very edge Of South street
piers and sips Coentes reef reaches up its head,
formidable witness OF what could not be done by
surface blastlng-the contract abandoned ana an
unpaid balance forieited-what further showing Is
neededp shall we pile Ossa upon Pellon OF evidence
and argument TO give quietus to claims which
1t is asserted that Hoyts Rocks and Bald headed
Billy ~ Hell Gate were removed by this process:
Let II be admitted The They were coat,tal pocket
reported 10y SAID b. Maiilefert.
Scientific opinion, deduced from careful observa-
ton and repeated experience, has long been Sails
lied 10 the merits or this pretentIouS system
rne results OF the late contract at Hell Gate nave
reiterated the Old story Three ROCKS were underta-
ken TO be removed by December l. Not one OF them
has disappeared, leaving the rock In the channel
untouched, OF which the survey was at hand months
before tue contract written TWO rocks in still
water and out OF danger were attacked. one OF
them, reauced IN It's decomposed and seamy strata
lrom thirteen to seventeen and nalf feet,
the otner scarcely scalped at all. The first
Ways Reef, materially unchanged in Its length
and breadth, sun has seven and hall
feet OF solid depth-its hears and core-lyng In It's
virgin bed On this reef at first the showing was
magnificent. Quantities OF rock were brought up
but their messy sides gave plain evidence that
ihal locally had been VISITED years before the year
oil grace just ended Examination discovered that
$1,000 poundsOf powder had been spent on that
rock eighteen years ago. When we consider the
price lor this w0rk-about f0rty-f0ur dollars per
cubic yard and facility OF the two rocks operated
up0n-we are led 10 conclude that something at
least handsome ought to be done Tor such liberal
encouragement IN cash.
Three years ago Mr.. Shelboume estimated the He'll
Gate work. part with another at eighteen dollars
per cubic yard. When the government started this
work on the contract system his bid appr0ximated
this lgure and ne thereupon contracted with the gov
ernmcnt in October 1865 for the removal Of two OF
the most hazardous and difficult rocks In the mid
channel OF the He'll Gate passage In speaking Of
this contract Brooklyn Bohemian sheet said IL was
libel on engineering that such proceedings should
be tolerated. IL Is now announced that. as result
Oh COSJ Vi WOIk RTcubIy
reduced the original official estimate being tribe
above forty dollars per cubic yard. II the cost Is
coming down to Mr.. Shelb0urneS estimate what
right then, claim has surface blasting, with re-
cord barren Of success, to contract at fOrtyOur
dollars per cubic yard not obtained by competitive
bidding?
Beginning with the contract system, had the gov
ernment continued IT, the work starting at "A low
figure would have Kept there, as q result OF expert
enCe gained, reasonable time being allowed ana
patience INDUCED till machinery could be con-
structed modified aud reconstructed as experience
sefguiued should approach the goal or success. AS
the mater stands to-day ~ 1t question oil powder
exploded OD the tops OF the rocks as against
suit OF eXperienceY What ls the experience of sur
face blasting? Fortyfour dollars per cubic yard and
q non pOSSunluS at that.
1t has been several times reported that MI Shell
bOurnes machinery was unable 10 withstand the
pressure Of the current and that he mad abandoned
the work and gwen 1t up as a failure Mr. Sncl-
bourne has but four drills IN succession within
o SINGLE year, the latest OF which, weighing twenty
fu. IL stood lmmo saby In the swiftest currents Of
Hell Gate. This drill was broken by COLLISION,
August IL, ana the contract expiring few DAYS
thereafter. renewal was not solicited. Although
the ayaiable appropriations have been absorbed 10
meet other requlstlons, that proved but broken drill
still remains the source OF more cheeriuiness and
nope than when It's embryo skeleton was nfSt photo
graphed in the visions OF thought.
one linal thing may be sad Of the He'll Gate work.
The field Is cleared OF It's mst5 and doubtful expe-
aIenls The plans have been sifted OF their chdn,
and many devices which were stubborn from the
Drain OF their inventors have been buried and for
gotten. The future Is clear and practical. Theory
and speculation viii sometimes take counsel OF hum
experience Knowing them, viii waive and frown
them ont OF The way.
YpyTH y3hTTr raM-