Daily Kennebec journal. [microfilm reel] (Augusta, Me.) 1870-1975, 1876-09-27

centric sleries, leaving pillars for the support of
the upper portion of the rock OF these there were
l13, the bell or roof of the excavation vary ing
from six o sixteen feet in thickness. The aggre-
gate len 9TH of the tunnels and galleries, which
were fns he'd In June last, was .425 feet S57
feet of tn anels and Z, SOS feet of galleries. The
total amo unit of rock taken out was ~ 4Sl cubic
yards. The rock is tough hornbleude gncss,
and lies in strata of various degrees OF inclination
presenting interesting problems. During iae
progress of the work topographc cal surveys were
continually made to determine the direction and
extent of the excavation, the usual meth ODDS of
triangulation and leveling beng employ ed. A
detailed survey of the upper surface OF the reef
was made 1871 by Mr.. William Preass rs sisted nv
Mr.. + Sylvester More than sxt en- thousand
sUuGdings were taken, each separately located, by
means Of instruments, from the shore. The roof
is in the shape of an irregular semi clip C, the
Ioa axis, which lies next to the shore benz 10
feet in length, and the minor axis, projecting
straight into the channel, about three hundred
feet. The cubic contents above the depth of
twenty-six feet at mean low water amount to
81 900 yards. The explosives used in tunneling
the reef have been nitro lyceiioe and its com
pounds, and gunpowder, the later being used
only when the rock was weak and seamy. AS
great had to be taken not to shake the
structure overhead by too heavy vibrations, only
one blast was exploded at time. After the exca-
Walton was completed, the work of preparing for
the blast was begun, and the roof pillars were
pierced with $3.50 dtill-holes TO receive the car
mite. The holes were made from two TO three
inches in diameter, and frem six to ten feet apart
with an average depth OF about nine feet. The
size of the holes, and their direction and dis
tances apart were made to vary according to the
character of the rock to be broken. On the 18th
inst, everything being prepared the charging of
the NINE was begun. Cartridges of vulcan pow
der, rend-rock, and dynamite were carefully
placed in the holes, the explosives being dis
tributed according to the nature of the service
required to be performed AT the mouth of each
hole was placed small explodent cartridge, com
posed of illuminate Of mercury and dynamite, with
wires to connect it with galvane battery. When
all the holes were loaded these wires were con-
nected with those running to the battery, standing
near the opening of the shaft, and placed in
position. Including the leads, the connections
and the fuses, about one hundred and twenty two
thousand feet of wire were employed. Owing TO
delays on the part Of the contractors in furnishing
the explosives, the work of charging the holes was
not completed until Friday evening. The wires
then having been placed in position and the shaft
cleared out, the large siphon connecting with the
river was opened, and the water was let into the
excavation, in order that it might be filed in time
10 allow the blast to be made at the appointed
hour.
THE COST OF THE WORK.
Following are the different appropriations made
by Congress for the He'll Gate and East River im