Evening star. [volume] (Washington, D.C.) 1854-1972, 1899-10-20

| 1899, under the different heads, may be
| classified follows:
Lining unllned portions of tunnei.-Con-
tracts Were entered into in February,
| 1899, for furnishing sand. cement, brick,
| special castings and bolts and the necessary
/ concrete and masonry work was begun in
| March and continued to the end of the fiscal
year, and 1913 feet of lining completed.
| Construction of invert in part of tunnel
| formerly lined.-A total length of 442 feet
| of this work has been done.
Repairing the defective lining.-In Cham
| plain avenue west above the arch of the
| lining, were found the largest voids, vary
| ing from fifteen to thirty feet in length and
| from three to twentythree feet in height,
ana averaging sixteen feet in width at the
| springing line of the arch. The debris, con-
| sisting Of tlmbers. cordwood, loose stone
: and fallen roof, was carefully removed from
! these voids and replaced with solid rubble
| masonry for a total length of 446 feet. This
| work Is now perfect thy solid and as sound as
new construction.
Arranging drainage of tunnel west of
Rock creek.-The plan of the board of ex-
perts suggested a brick conduit for carry
| ing the drainage to the Rock creek sump
| but 1t was found that the better plan would
| be to lower the level of the bottom of the
| tunnel or invert to the required grade. This
work was begun on March 10. 1899. and
| continued up to the close of the fiscal year.
The greatest excavation was eight feet,
and from this to nothing as it reached
| grade, Two thousand eight hundred and
tWelFe llHedr Ieet OF grazing nave been
| completed, leaving 615 linear feet to finish
| the cutting.
Iron lining OF tunnel at Rock creek.-The
work of placing this lining was begun on
May 16, and at the close of the fiscal year
100 linear feet had been set up and backed
with rubble masonry. The lining consists
of cast-iron cylinders nine feet in diameter
in the clear. the castings being in segrnents
four feet long in the direction of the axis
OF the cylinder, and Of such dimensions that
each forms a vousSoir of one-eighth the
cylinuer. The thickness of the plates is
one and one-half inches, and they are bolted
together on the inside horizontally and
longitudinalIy with one-inch bolts. At a
point where a large flow of water came
through the roof Of the tunnel from Rock
creek the rubble masonry backing could
not be laid. Here holes were bored in the
iron lining to allow the water to escape into
the lining, and these holes will be used for
pumping grout into the spaces back of the
lining, which have been filled with dry
packing.
Filling voids in dry rubble backing.-No
work has actually been done under this
head, as it Is deemed best to leave this
until the portion to be worked is entirely
free from other active operations. This
work and the washing of the interior of
complete the underground work
With a view to testing the efficiency of
srouting, model twenty feet long was
built above ground to represent the dry
stone packing of the tunnel Timber lag
ging represented the extrados Of the brick
lining and also the sides and roof of the
tunnel Grout consisting of one part n.y.
drauiic cement and two parts sand with
water enough to render the mixture of