The New York herald., 1870-04-30
BLOSSOM ROCK.

Thn <zrs..s uu..s In San FrauciscO Harbor-
TVveut y-Threc Tens Of Powder Exploded-
Full Particulars Of the Excavation and De-
tails Of the Piazza Novel Ensineerins
Wsrk.
isan Francesca lApr!l sal Correspondence Chicago
Blossom Rock the most dangerous obstruction In
this ha Dor, WAS blown up to-day at two o'cosk.
Twenty-three tons OF powder were used. When this
Immense quantity OF powder was touched on the
water, apparently 100 feet IN diameter was thrown
flea 0 with smoke and stones-she latter going iaf
above the water Between 50, 0c0 and 10000 peope
witnessed the explosion. 1t was scarcely pr
eoppased the blast Colonel Won % sanmidt % Civil
Engineer, began the work completed by this
explosion between four ana Ave months ago The
means adopted for ats removal said to be entirely
novel In submarine blasting, and the engineer under
took the experiment ~ much risk. HIS idea for the
piler annihIation OF the rock, when put before the
public, LETT httie doubt that it might prove success
iui though many doubted that the work could be
ot the wafer at low de and situated where the
water rui.ed over II in power nj swells and " tn
great force. The first work done under Colonel Won
hmldrs plan was to make q careful survey
OF t0e rock, ascertain where 1t dipped in and
where 1t proecte SO that In the work OF eX-
space might remain TO resist the pr ss1re O the
water. This was carefully done, and from 1t plans
around that part OF IL through which the shaft was
70 be sunk TnIs was ound co be very difficult.
The Golfer dam IN its place. and then scow
was built around It, into which about 300 tons OF
stones were thrown. The dam was lined around
with bags OF sand TO more eilectually keep out
the water, and when this was complete an iron
turret was placed inside OF IT, This taret was
hree oa sunn 'n1 IN ts Mace
A platform was then erecled on the rOck, ffly-
| six feet III length and about twenty in width. On
one end of this al engine and complete holsf1ng
apI arasus was place and at the other end shanty
was erected, containing six sleeping apartments aud
| a Kitchen which was also used as an ca ing room by
|
| then D'gun. When the shllt ha reached u certain
depth small cylinder was placed inside the original
tulre winch made the hosting OF the la last rom
| below more convenient. The object was to scoop
ont the cenre of the rock producing cav " inside
measuring the clear, from the highest point 70 the
| bottom, twenty-five lees, anu leaving crust
! or stratum OF about SIX feet thick 10 resist the
gress; this crust or stra un to he blown up by pow
! der when The remainder OF the work inside had
been completed. TO do tn s, however. was not only
| difficait, hut peri oaS A the excavation became
larger, the crust OF rock LETT anding would natu
| raily become weaker and likely to cave III. To pre-
vent this pu OF rock lett standing al short
intervals from each 9th r. until the m OF TX ieet
| was everywhere reached. Then II became ne essary
to remove those plilars Before this was done
uprlghts of heavy tmbers were set thlcKly arc ana
the cavity TO su py tner place. All the Dilars were
then removed except the two main ones, which stood
| last moment possible. The space excayated mea
Eured In the clear 40 by 80 feet and II Is es mated
The shape OF the surface OF the rock was near oval
but FOR dis ance OF about l20 teet 1t soped very 1T
tie The height OF the hi2 hest pillar inside 20
Ieet and the lowest feet. The stone was porous
sandstone. When struck with q hammer 1t fell to
PIE es readily ana revealed series Of seams running
through iG. There was no mixture OF ate or gra.
n te any OF the harder kind OF stone in H. from
which II seemed evident that 1t would blast we'll
The plan OF explosion was as fOllOws:-Of the
twcnfy-tilree tons OF powder used, about half was
contained in English ale casks double coated with
heavy iCh varnish inside and outside, 20 as to be
waterproof Tie other half OF the powder was in
seven boiler tanks Of wrought iron, firmly boiled,
the largest measuring eight feet in length and two in
diameter. The barrels were placed close to the side
~ the excavation, near the junction Of the
arch or roof with the floor, as to blow
excavation reached. They were placed resting
on their sides. The seven boilers were lati
through the centre OF The chamber, the larges In the
middle, where the roof was CHEST rns DISPOSE
tIO1 was made TO eq afize he frce each part OF
The rock. pc iorated piece OF gas pipe two and
hall feet In myth, charged with tine guupOwder,
ran into tie barrel from eacn tnd and piece six
1et long to the Hers, charged In he me way.
Thes different uDes were Connected WI insulat d
ell ctrica wires, which passed ffom one ba. rel to
another, the ed in each tube consisting OF fulml-
ma ing cartridge.
The insulated eectric wires connecting the bar
re's W r. inca ed In gutta percha. When the
powder was arranged III the excavation aad the
connections made secure This wire was drawn up
through tube In The sDaft and placed ON board u
bark situated ABOUT 1000 feet from the rock. Hee
II was lected with an electric battery. The
coitr dam was then removed and the water per-
mltted to al up the excavation and so act as a
timping
bnt II Is beileyed that the explosion has been
tlaI