, 1870-04-28
BLOSSOM ROCK.

The Grent Hast in sam Francisco
EIArboF F-T<enty-thrcu Tons OF
Powder ExpIoded-Fust Pnrtieu.
lars OF the Excavation and Dr.
tails Of the P1an-A Novel EnEt-
neextnE Work.
SIN Francisco, April ~
Dlossnn Rock, the roost dangerous ohstruo-
ton IN this hatbor, Was blown up to-day at3
O'Clock. Twenty-thrco tons Of powder wero
used Vixen thiJ immense quantity Of powder
was touched oil, the watcr. appsrent.. 100 feet
100 feet, the centre being filled with sunke
md atonea-sLe 1.tter going far abo.e the
vntet. Between 81, 600 and SO, ,o00 people wit
nessed the explosion It Was scarcely per-
septbs u Ss.f ths f a55a 9s5 yan sssR Ri haa c1
Euc2ueer, began the work completed by this
exnioeion, between four and i've months ago.
The means adopted for ita removal 70 asid
10 be entirely novel IN submarine blasting. and
much 1ssk His idea for the utter snnihilation
Of the rock, when put before Che public, lett
little doubt 1hAt It might prove successful.
though nsny doubted that the work could
Be dono. BLOSSOM Rock WAS sig feet below
the surface Of the water At low tide. and sltu-
sted M where the water rolled over it in powerful
ewella, and with great force,
The t1at wofk dono under Cnl0nol Won
Schmidt's Plan wss to make q careful survey
Of The rock, ASCERTAIN where il dipped in and
cavation atterward accomplished sufficient
space might remain to resist the pressure Of the
water. This was carefully done. and from it
plans we're drzwn Of tho rock. The ucxs work
xxs to constructs wasc1-tlSat Golfer t1Am on
the rock md asonnd thas part af it through
which the shaft was to be sunk This wAs
found to be reIy difficult The cofcz-aam
wzs put in its place, k1.l then sSow was built
around il, into wf.i:h about 80 tous Of stones
were thrown. The dam WAS lnr.I around with
A. No. H. -- ~+4f
tLe water, and when this was complete An iron
turret wss placed inside Of it, Thus tusrot
xss imtelaeA OF kunk IN the rock distance OF
three feet, and closely cctue1tcd in its plaee
A platform WAS then etected on the rock, dfty-
sir feet in length, and about twensy IN width
On oue end OF thia m engine and cofaplete
hosting apparatus MAS placed. and at the other
end a sLapty wAs erected, containing aix sleep
ing apa1trnepss md \ kitchen, vi. .ch waa also
nsed Is N eAting Spom By tho vurknaen- The
s;nfina Of the main shaft was then begun
Wheu tho sh.ft had reached certain depth,
txaau cylinder wAs plsced insids the original
turret, which made the hoistinS Of the ballast
from below nore convenient.
The object Was to scoop ont the centre Of
the rocf. producing cavity insiae, measuring
in lie clear, from the highest point to tho
bottom, twenty-five feet, and 1esving crust
or stratum Of shout ai1 feet thick to resist the
pressure Of tho water while the work vhs IN
progress; thia crust or stratum 70 be blown
10 bs powder when the remainder Of the work
inside had been completed. To do this, how
ever, w.s rot only difficult, but pesilous- AZ
the excavation became larger, the crust OF
rock left standing would naturally become
weaker, and likely to eave in. To prevent
this. pii1ars Of rock were left standing 1t short
intervals from esch other, until the limit OF
81 feet was everywhere relched. Then
it became necessary TO remove those p4l-
lars. Beforr this was done uprishts Of hessy
titnhers we're set thicklr Aroand tho cav
ity to supply their place an the p1lAfs Tete
then removed except tha two main ones, Which
rteod u. either side Of the shaft These were
leit to The La. moment possible Tho space
excaYated measured IN the clear no BY so feet.
and il is estimated that about 10, 600 cube feet
| Of stone were taken out. The ah.pe ot the
distance Of about 1eo feet il b!opea very little,
! Tho hight Of the higheat piAsE inside was %
i feet and the lowest feet The stone WAS
! porous sandstone. Vixen struck with ham
mer It fell to riseea re1aily. md reSealed
series of seams running through it. There
| was no mixture Of slste Or granite, or any of
the harder kind os stone IN i, from 1hich it
| seemed evident that it would blast well
Tho plan Of explosion WAS A. foIlows: Ot
the. g tons Of ponder used. abont hah ras
with heavy pitch v.1nish inside and outside:
30 10 10 be v1te1-proof. The esAaz half Of
| the powder was In seven boiler tanks OF
wrought iron, firmly bol.ed, the largest nnas-
urinH eight feet IL length and t"o N o1auaste1
Tbs barrels were placed close to the aida Of
the excavation, near the junction OF the arch
OF ROOF with tho floor, 30 "a to blow away the
nrrh from the lowest point uf excavation
reached They wero placed resting oI
their sides. The seven boItera vera lait
through the centre Of the chamber, the l4Tsos1
in the middle, where tho roof Was highest
.. This disposition WAS made to equal!ze the
fnce on each part Of the rock A perforated
piece Of gas-papc, ~ feet in length. charged
!! aith hne gunpoudcr, ran into each haz1c1 frog
,. The end, and piece feet long into the boil
era charged in the e4sne rvs.- These QluaIen
I tuLes were connected With insulated cfcctrica
j. wires, which passed from one barrel to N
other, the end in each tube consisting OF tul
1niuatiug cartridge. :,
The insulated electric wires conncctins ths
) barrels were incased in gutts-pezehs. Whe1
tho powder Was 1zEHuged in the excavstlo''
and the connections male secure- this wire VA
drawn up through tube in the shaft, ant
PLACED On board bark sisnased kbout 100
. fact f1un tho rock. Hora it was conuectet
with An electric bzttery. Tha conet-d1m Wa
then removed, aud tho water permitted to fl
up the excavation, and 40 act ID tauping.
no fun survey Or soundingB haro Jot beeI
made, bnt 1t IL believed ttat tho explosion ha,
. | been entirely sucrtsHtul.