The New York herald., 1870-05-06
HE'LL CAT E..
The Work Goes Bravoly on-What Has Been
Accomplished Difficulties in the
Way" Blossom Rock" Nota Cir
oumstance" in Comparison
Views Of an Expert

The accounts, DOtn Dy telegraph anu mall rccelveu
and Published by the HERALD, OF the destruction Of
Blossom Rock In the harbor OF San Francisco Mt one
terrific blow, have very naturally revived public
curiosity and even anxiety as to what's being done
with Hell Gate For nearly twenty years, so people
began talk practical and theoretical engineers
have been at work. almost innumerable devices were
tried, and what was the results The rocks which OBJ
sruct or at least hinder and delay navigation at He'll
Gate and render It dangerous are still there TO nearly
their former extent, while an energetic German en-
glneer, after scarcely more than six months OF work'
relieved the harbor Of San Francisco OF one OF lts
most dangerous impediments Why, sad these
same people, cannot the same system whlch plew
Blossom Rock into atoms at one Charge DE 'rieu
here9 Why could not Hell Gate be cleared aiso py
submarine mining and blasting from belowf
Theorizing on such a subject flows very gDly from
the lips OF people not accustomed to the searching
inquiry demanded by the laws OF the exact sciences.
These compel the taking into careful consideration
all the circumstances OF the case and its surrounding
conditions And after such inquiry II has generally
been found that no two cases to be operated upon
are ever alike, and that means which proved emf
nenty successful in one, win but a useless waste
Of time and money in another. This Is true Of the
subject now under consideration. Blossom Rock,
which now is no more If the reports received be
fully true, when compared with the rocks at Hell
Gate, was Ike sheep 10 an elephant The SUBJ
joined communication, from one who las tried his
energies on some OF the rocks at Hell Gate, gives
several reasons why The process SO successful IN
San Francisco harbor may be found imprac-
ee Roek may ouy yet a,o 1e
5000 cubic yards Of sandstone, while the rock at
Hallett's Point alone, on which General Newton ls
now at work. has 1000 cubic yards Of stone as hard
gness, the weight Of which averages from l60 to
ITO pounds per cubic foot. Another rock at Hell
the "Grldron measures over i5O 900 cubic yards OF
the same quality Of stone. These figures OF them
done here and that lately accomplished win Blossom
kock.
WHAT IS BEING DONE.
Yet, this tunnel ing process has been adopted by
General Newton in his efforts TO remove the rocks at
Hallett's Point. He has built substantial Golfer
dam, abutting on dry land, much Of the rock
as is usually visible at low water This dam, being
OF irregular shape, Is nineV-one feet In width In one
direction, and 140 In another, where 10 is widest
Within this dam and almost to It's full extent inside
shaft has been sunk into the rock to the depth OF
thousand cubic Yards OF rock have BEEN
as much as the whole OF Blossom Rock contained.
rms snat WI have TO DC exeavalSa 70 ngther
will have been reached and the mining OF the
'chambers" VIII commence. These chambers VIII
above central point like the radii OF circle
When they are completed, the intervening rocks will
chamber under the whole of the rock, leaving roof
above of about ten feet in thickness supported be-
low By Ts It Is M @ 2ayar w
from above and on the sldes From the point where
the inside OF the roof or this chamber touches
the level or floor. the drilling process WIN
under which the chamber is excavated,
viii be blown up OF one discharge OF
nitro.glycerine. Colonel Won Schmidt used twenty
four tons OF gunpowder on Blossom Rock. II the
same quantity in proportion, were employed on the
rock at Haletts Point, 400 tons would be required,
the explosion Of which would destroy Astoria, Ra-
vensw0od, Harlem ana good part of Yorkvlle and
change into wrecks the public buildings on wards
Island and probably on Backwells Island alO. No
such quantity OF explosive material is needed, how
ever, since much less Will do the same worA--lemo
ish Hallett's Point rock completely and pjurc not
building In the neghborhood.
1t Is but proper to say, however, that the opera
tions at Halletts Point are carried on somewhat In
the light OF an experiment. Two things are taken
into account-the expense and rapdity OF the work.
This subaqueous mining process II is believed, may
be found the cheapest method while the
these calculations should be found correct,
1t Is probable that when the time comes
TO remove the Grdiron, that hIleous monster
OF an obstacle to navigation, both methods may be
employed. The smaller rocks it is hoped to get rid
OF While work is progressing on these two huge Oh
Hogs Back and other similar places will be sur
rounded by rubbe walls, which Will prevent vessels
from being drawn upon them by the rapid current.
Ways Reef and Shelldrake are no longer terror
TO vessels or less than eighteen feet draft Professor
Mailleiert has been at work upon them with his sur
there is now depth OF eighteen feet upon them at
low water. His contract having expired ana not
being renewed, the Professor has ceased operations
General Newton thinks that the passage Of He'll
Gate will be entirely cleared and rendered safe for
navigation by the plan pursued by him in about four
years II Congress be not too mserly in the appro-
priation OF the necessary funds.