Perrysburg journal. (Perrysburg, Wood Co., O. [Ohio]) 186?-1965, 1877-10-19
A Mining Tunnel Thirty-one Miles Long.

After thirty-three years of uninter-
rupted labor the great undertaking of the
Rothschonberger water adit is so far
completed as to admit of its use. The
method of draining the Freiberg mines,
Saxony, by means of deep tunnel, had
already been discussed in the beginning
of the present century, as question of
necessity for the future mining prosper
ity of the vicinity; and undoubtedly the
Rothschonberger tunnel is the greatest
work of the kind that has ever been under
taken to aid the exploration of mining
district. Other great adits, such as those
of the Hartz Mountains and the famous
Sutro tunnel, fade when compared with
tunnel which has already attained a
length of more than twenty-six English
miles, and will be with its branches,
when completed, more than thirty-one
and one-half miles. The plan was to con-
duct the water from the Freiberg mines to
the nearest practicable point on the River
Elbe. Rothschonberg, twelve kilometers
above Meissen, was chosen as the most
advantageous place for the mouth, on
account of it having the lowest level at
the shortest distance from Freiberg. The
preliminary surveys were made in 1S43,
but the work was not thoroughly taken
in hand until the third quarter of the
year 1874. Since that time the driving
of the tunnel has been increasingly car
ried forward, but coupled with many
hindrances and difficulties, such as quick
sands, immense quantities of water, ETC.,
which have trebled the cost and retarded
it's completion.
The tunnel is ventilated by eight air
shafts, and lies some 400 feet below the
deepest Freiberger water adit. 1t has a
uniform height of 994 feet, with some
what smaller breadth. The present length
of the adit with its ramifcation is Al, 600
meters tall of which length is now in
usel, and will be when completed over
81 900 meters, or thirty-one and one. half
miles. The cost of the tunnel is esti-
mated at 12, 900, 900 marks, or 81, 900, 900,
and will be paid for by tax on all
the mines which it directly benefits.
The gradient of the floor is only 0.03m,
in 100 meters. This small gradient may
make it necessary to clear the tunnel oc-
casionally, but this can be accomplished
without difficulty with suitable boats and
dredges. Five miles of this tunnel are
perfectly straight, without the slightest
curve, and along the whole length the
curves are very light. One rather in
teresting occurrence during the past yeal
was the striking of an old mine, OF
which no maps are in existence. The
mine is probably more than four centu
ries old, and the timber which has been
used as supports, ETC., was found foI
10 nrt a,1rnA Trun uaiYae
were also struck, but only one of them
will be exploited. 1t is rather remarka'
BILE that nearly the whole driving of the
tunnel has been done by hand, Burleigh
drills, driven by compressed air, having
been introduced within the past year
The rock throughout nearly the entire
length is solid gneiss, which accounts fol
the great time that has been taken to the
work, it being necessary, with hand bor
ing, to put in as many as from forty tC
fifty holes to the face.
Thenecessity for the continued prosper
ity of the Freiberg mines, which have
now been worked for about seven centu
ries, may be gathered from the fact tina
at the present time there are more thar
5000 laborers, with their families
amounting altogether to some 10000
persons, who derive sustenance from the
mines and metallurgical works connected
with them. 1t may reasonably be ex
pected that the Rothschonberger tunne
will give fresh impetus to the Freiberl
mining, and considerably augment th'
output of ore, which has of late year
somewhat fallen off, owing to the i'm
mense quantities of water which con
tinued to food the mines, and prevented
the veins of the ore being followed anC
worked below certain depth.
Saxony may well and justly be prou'
of tunnel which is without doubt tn
longest in the world, and which has re
quired SO much time, perseverance, skill
and labor as the RothschOnberger waite
adit. .-Scientsfe AmertoGn.