New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1869-01-12
massage. The schooner Is loaded with logwood ana ID
said 10 be In a very bad condition
HELL-G1TE.

| rur REMOVAL OF TIE OBsTUCTIONS BEGUN
| IMPROVEMENTS IN SUBMARINE ROCK BLAST
| ING-PREvIOUs OPERATIONS IN THE GATE.
| Mr. Sidney +. Shelburne, contractor, yester-
day entered upon the work OF removing the flying ran
Rock OF the most dangerous DISTINCTIONS u TIC pas
sage OF HellGate. This rock Is situated ABOUT uway
between Wards Island and the village OF Astoria ur
sheburne's apparatus is of his own invention ana Is DO
leved to be great Improvement upon any macnhoiy }
vet used for the drilling OF sunken rocks III cOnssts VI
| q steam engine and drill, which arc III
| closed In q watertRht, mushroomshaped chainoci
and sunk to the bottom. The idea is certainty noVel
but its value will probably DO put to practical Iest
the end OF the week The chamber which ABOUT
four feet high and six in diameter Is made very heavy
and ballasted weigh in water about 1000 TO-
This great weight is necessary account Of the immense
switness OF the current Hell Gate the tide sometimes
running there the rate OF eight knots an hour Inc
shape OF the chamber is such that when sunk u VIII oher
proporonatey greater resistance to the current tpa
the shell Of tortoise 1t has number OF steel claws or
iukes which will also be Iseryceabe to prevent shdlnR
conducted the engines Enclosed nthe chamber
through flexible pipe which is surrounded by second
pipe, used to convey the exhaust steam. and which
steam jacket Perhaps this Is the most likely
10 give trouble o. any portion OF the machine The diam
cer OF the external pipe is about six inches and Its sur
face offer considerable resistance whom the tide Is
running swiftly. The bending Of the pipe may also OBJ
the passage OF the The drill which Is TO De
used IS 2i inches in diameter and has bored
through granite at the rate OF nearly an
inch per minnie. The shaft OF the
drill about niue feet in length, and will bore hole
from four to six feet In DEPTH according to the position
OF the chamber the bottom II the chamber rests
Nat surface, the maximum depth will DO reached. The
steam engines used to turn the drills MS before stated
incloed in the chamber They are constructed to
per minute. When the drll has been sunk to
It's extreme depth, by an automatic movement its
the chamber is ready TO be lifted and dropped over
another place. when number of holes have been made
divers descend and charge the cavities with nitro
glycerine, other explosive compounds. After the
Morris & Cummings patent graphing machine The
appropriation under which the present work is being car
red on IS only ss5 OOO having been cut down from
10 that amount by our economical representatives. at
Snpveys Of the Hell Gate Channel were first made by
Admiral Porter. then lieutenapt about 20 years ago
Subsequent surveys have been made By Messrs DAVIS
the late Prof Bachc superintendent Of the T. s. Coast
Survey The work making these surveys 10 ono OF ex
nearly two years finish mapping of the bottom
q Hell Gate and that has already taken two months
10 eurycy tho two rocks which Mr. Shcburne has con-
tracted to remove. Nothing actually done to im
prove Hell Gate until about the year 1854 AT that time MI
ing operations the West indies offered rocks
at Hell Gate by GEN Buffers process OF concusson This
was found TO work tolerably well under water Large
quantities OF powder were exploded on the surface
aud by the side OF the rocks, aud, the mass
OF water acting as fulcrum, tho project
inc masses were brotan Of Me- asS fts spots were
ed, and the navigation OF tho East River was
made very much safer The following extract from the
United states Engineers report VIII show that W Male
fcrts plan is now longer practicable when Pot
attempted Ivy the process OF surface blasting
first 10 feet in vertical hight were removed by -
charges The next three feet In hight required li9 add
Ona charges. The next IA feet I'm vertical hight, as re-
ported. required but 30 additional charges AZ TINS
period the work passed into the hands OF tho United
States Engineers, and survey made, which
proved instead Of 2)i feet having been removed
by lthis process claimed there had been nctually
little over Is feet" subsequently, the
engineers fired about 90 additional charges, and
reduced the rock depth of about 20 feet no mean low
water. It will be seen how deceptive the record OF
work accomplished when estimated by vertical hight,
must prove Two hundred and cightyfour charges
reported have reduced the rock 10 feet In hight but IL
required additional charges 10 increase that depth
about foot The inference IL obvious that the process
promised great results long rs projecting and salient
points offered 10 the explosive effects OF the charges
bat a lamcntabc falling off took place when uniform
lAt surface was reached At Pot Rock, depth or -
feet al mean low promised, and about 20 feet
attained; and far as know 10 the writer no entire
rock In York HarbOr has been removed by The pro.
cess OF surface blasting the required depth OF -
low water. though frequent trials have been