The Cecil Whig. [volume] (Elkton, Md.) 1841-current, 1885-08-01

was not inc design 10 remove the rock
as much as possible by means of these
tunnels-owing to the fact that it would
be cheaper to drcdge the broken after
the eXplosion-which were only OK
pected to serve as passageways honey
combing the rock and through which
access could be had to all parts in or
der to place the powder. Absolute
regularity in the spacing of the galleries
could not be maintained owing to in
equality in the texture and formation
of the rock.
Thus was formed an immense
chamber, averaging about 10 feet from
floor to ceiling, having a stone roof
averaging about IS feet in thickness
and supported by 467 rugged and mas
sive columns. In this chamber, run
ming parallel with the East River, are
galleries, the longest measuring I 200
feet, and running at right angles to the
stream are 46 galleries, the longest Of
which is 625 feet. The area covered
by the chamber is about acres. The
aggregate length of the galleries is
2I,67o feet.
The mining operations were not at
tended with unusual risk either to the
men or the work the main danger was
from the flooding of the mine through
the opening of fissure, or the meeting
with rock keyed the wrong way"
which would admit the water in guam
titles too great to be handled by the
pumps. Fissures were frequently en-
countered, but fortunately none of ex-
cessive size the large holes were plug
ged with wood, loose filling, such as
cement, being unavailable because of
the great pressure OF water, some 26
pounds to the square inch. To escape
the drippings and in some cases the
pourings from the roof, and to enable
the visitor to walk dry shod through the
small brooks running down some of the
galleries, he is, through the kindness Of
those in charge of the work, encased
E.o,,, lo,,l Co..
The northeastern portion of the ex-
cavation, having an area of about one
acre, was through rock very irregularly
assured, and as the roof approached
closer to the bed of the river great care
was exercised in driving the headings
in some places it was found expedicnt
to support the roof and sides with
heavy timbers. In order that the cav
ing in of any part Of this section should
not flood the main work a strong door
was early built in the gallery connecting
the two sections. Attached to the outer
edges OF this door is a rope, leading
over pulley in the casing and along
the gallery to the shaft the door can
thus be easily and quickly closed, should
it become necessary at any time to shut
off the weak portion of the work.
Thirteen thousand two hundred and
eighty-six holes have been drilled in
the columns and roof, the holes being
3 inches in diameter and having an
average depth of 9 feet these holes, if
placed end to end, would reach oyer
20 miles. During the progress of the
work an accurate plan was kept, show
ing the location and number of each
hole, together with its inclination and
depth. The holes in the columns are
about S feet apart, and extend upward
at an angle of about IS degrees; the
holes in the roof are about 4 feet apart,
and are at an angle of 60 or IS de-
grees. No holes were drilled near the
floor. Each hole will be filled partly
with 'rackarock" powder and partly
with No. I dynamite. A small car is
provided with several frames, made to
fit on top of the car, and each being
about the size of the car; the frames
can be placed as needed, one on top
of the other, thus furnishing a platform
from which the holes in the highest
galleries can be reached. The track
consists of two movable sections, about
IS feet long. Should no delay occur,
it is expected to complete the charging
of the holes by the first Of October.
The next operation will be to remove
all the machinery and buildings, and
the top of the island down to the waters
edge. Of course, much of this work
can be done during the time of chars-
ing. The mine will then be flooded
and the charge exploded by means Of
electricity.
Extending around the southern part
of the mine and along the eastern ex-
tremity is second ditch, connecting
with the first third ditch leads from
the eastern side to the stump, just east
of the main shaft, where pumping en-
gines having capacity of 4 200 gal
Ions per minute are located. This plan of
draining the mine by means Of ditch
around the extremity was made neces-
sary by the slope of the river bed; in
order to leave sufficient rock in the
roof, the galleries slope downward from