The daily dispatch. [volume] (Richmond [Va.]) 1850-1884, 1876-09-20
s. J, a covered

>in thick tpper ap, en- y zco s9e.',..
WitEk uttta s46Tchay the gut ,ercha notoniy
ess as d cdshions but also preventing any
sftittffY by Wxter Of damp. he Whole fuse
is thiekly Epsted with paranne, ana y tnen
.eneiosed in.ftin cartfidge.case containing
dynamite, and is nermet ically sealed, ADouS
two feet Of each OF the wires OF tne Iuse
hang ont OF tho printing cartridge 90 % 70
enable the easy attachment o. tne paIssIys-
wire after the cartridge is placed IN posi- 'sis
ton. .s 81 ss.ste-e't
The charging Of all the one hundred ana
eighty-four groups is now pretty WEI! co .l.s
pleted; the printing ana attacnhs VI sno
network OF battery wires alone remaining
to be, carried ont before NIL is ready for the
blast. About fifty feet south OF the smart .
bonlb-proof similar to riie-pits, but OF
course far stronger, has been constructed
of stout timber and earthwork. In tnls
structure the batteries, with about one
thousand cells. will be placed. wires WIN
be run direct from the batteries 10 eacll
group Of charges; the first charge connect,
ing with the second by wire, the second
with the third, and so on, till every charge
IN the group is brought into Indirect COM
munication with the batteries. AT the time
of the great blast these batteries will be uls-
charged from safe distance by means OF
closing circuit, and the next instant .tne
great explosion will have taken place. 1t
is believed that the event will occur on
THURSDAY next, as near the middle OF the
day as high tide will allow. However, In
operations OF such magnitude 1t is impossl-
BILE to foresee what delays may occur, even
when everything is apparently ready ana
the last moment OF hand. In any case tne
explosion must take place very shorty, In
consequence Of a liability to low tempera-
ture at any moment. Nitro-gly cerlne freezes
at 400, and when frozen 1t will sometimes I1l
explode under a very slight shock. Inc
danger Of q premature explosion under
such circumstances would pc manl1estly IN!
creased to q somewhat alarming extent ZOE;
those employed in the work, in addition 70
the risk of partial or complete failure OF
the enterprise involved in premature eX-'
plosion. fj.'sf'i ~ = -.
THE PROBABLE RESULTS.{!fi n-r .
AS to the possible or probable results OF
the blast the only submarine operation OF
the kind which can at all be named in COM
parison with it-that of the blowing up OF
the Blossom Rock in the Golden Gate OF
San Francisco on the 23d OF April, 1870
was, though in every way successful, COM
paratiyely q small affair. In the body OF the
Blossom Rock large chamber 140 feet long,
go feet high, and with maximum height OF
- feet, was blasted out, four rock piers being
left to support the roof Of the excavation
where the superncumbentw weight was great
est. and the remainder being shored up with
stout timbers. This is 4 mere hole COM
pared with the: mine under the Hallets
Point reef. the ramifcations OF which cover
| two and three-quarters acres. AS matter
OF fact, there is not the same cubic space In
the whole Blossom Rock chamber rs there
is in the Hallet's Point shaft alone, the shaft
being, rs stated, III feet by g. feet, with a
depth below low water Of 80 feet. But In
addition to the vastly larger floor area OF
the Hallet's Point mine, its maximum
height is 90 feet against II feet in that OF
the Blossom Rock. The charge OF the blast
at San Francisco was $4,000 pounds OF
ordinary powder, contained in ale-casks
and old iron tanks, and If the reader
will refer to the difference between the
explosive powers OF gunpowder and
nitro-glycerine before mentioned, and
then calculate the number of cartridges to
be exploded at Hallet's Point at about
12.O0O-the cartridges being three inches in
diameter and ranging from nine to twenty
four inches in length-some sort OF mental
comparison can be arrived at between this
charge and the one to be fired at Hallet's
Point. Now. at the time Of the blasting OF
Blossom Rock, a column of water 200 feet
in diameter was thrown into the air to Q
height variously estimated between 200 and
800 feet Around this column was an outer
ring of water OF enormous bulk, about sew
enty feet high, and gradually rolling away.
1t will be seen that the effect of the explo-
sion was almost entirely upward. Nitro
glycerine, and Of course dynamite, takes a
wider explosive range, and a far greater cir
cumierence of water disturbance may be
looked for at Hallet's Point, Nevertheless,
it is anticipated that very fine column OF
water will be thrown into the air to as great
height, if not greater height, las that
which was seen at San Francisco. twill
be a magnificent spectacle as witnessed
from the more elevated portions Of the city
which command view Of that portion OF
East river. In the explosion at San Fran
cisco the rock was successfully broken up
and the debris afterwards removed; and
there is every reason to hope and believe
that the explosion next Thursday will
prove equally satisfactory and gratifying
not only to those who have it in charge, but
to the thousands Of navigators OF the Sound
and the East river.