The morning times., 1895-07-07
Down on th6 Rivers
Where Men Hr6 al Work.
Repairing the Defective Piers of the Aqueduct
Bridge-DifferenCe in Engineering Between
Now and Fifty Years Ago.

ranean river The edges OF the stones
are hid in the mud that has washed in
through the cracks in the masoncry and
in the angles OF the stones this mud is two
to six inches deep.
MOVING GREAT STONE BLOCKS.
The men slowly and cautiously move
these huge blocks of sandstone from their
beds OF mud with their crowbars aud hitch
the graphing hooks TO them. The thirty
horse power Ledgerwood engine that
stands on The northeast corner of the crib
Is set to work, the steel ropes stretch and
strain as the ton or more Of rock is swung
into the air. the boom of tie great derrick
Creaks on lis iron hinge as ii swings about
when the top of the CRIB is reached. The
stone is poised a moment over the open
work Of the Golfer just inside the wall and
then let loose. ii drops with thld into the
big pocket below aud the derrick returns
for another lead.
The next trip brings huge bucket of
mud and water mixed with fragments Of
stone from tie size of Il goose egg To fifty
pounds. Il is shoycled in quickly by the
wor6men aud makes the same journey 10
be dumped between the timbers Of the
cribbiug All the while this work gees
on stream of water about The size of
woodland brook or branch is flowing in
from The leaks at tie bottom OF the Golfer
aud the pump is throwing il cut at the
rate of 5000 gallons a minute.
There is a well al the bottom where
this section Of brook empties aud into
this the uozzeI Of tie pump dips with its
sieve to strain ont stones and chips, and so
the interior Of the place is kept dry and
the woTkMen ale able to go about freely,
stepping back and forth over the little
stream that represents the great PO-
tOnlaC iuS de the dam and left alone would
in q few hours fiji tie great structure to
its brim thirty feet above. Some idea
OF the strength required OF the Cribbing and
tie difficulties encountered in putting and
keeping il in place can be drawn from the
pressure on the bottom, 200 pounds TO
the square foot
HOW THE DEFECTS AROSE.
How did the stone work at this pier
happen 10 need repair? is asked sometimes
The construction was done by Col TrumbuH
about fifty years ago ana was considered
very substantial fit 10 last for a century.
The other pIers do NOT seem 20 be affected,
except that a little cement Is washed out
here and there. Why this should have
suffered so much more is not known unless
there was 4 defective stone ia Its make up.
IL is located, however, where the force of
the current is strongest and the first wear
might be expected.
Some points brought to light by the work
show what advances have been made in
engineering in the past fifty years. The
bottom of the river upon which the founda-
ton Of the pier was laid, is uneven, indi-
eating the difficulty in those DAYS of re-
ducing solid stone under such conditions to a
smooth surface This viii be done readily
now by the use of steam drills and blasting.
Again the great wooden timbcrs holding in
place the walls and about which the pier
was buIit remainembaddedi in tbemasonTy.
They seem not to have known in that
I II.
them out after the work was finished We
shall build some trusses at the side and drive
them out without much difficulty"
Steam was as new in thatday aselectricity
is now and many materials were in a crude
state comparatively Hydraulic cement,
| for instance, was practically unknown.
NO DANG ER TO THE BRIDGE.
How soon viii the repairs be completed?
| That is not so easy TO answer The
excavation VIII be done in ten days Then
! the reconstru ctiOn VIII begin and be
| pushed forward rapidly. Such caution
viii not then need to be observed to prevent
accident. Every step VIII be with known
materials and TO do something already
/ planned. Three relays of men viii be
/ employed and the work viii be kept going
steadily night and day. Electric light
VIII be used When the foundation of the
1 pier is renewed the dam must be removed
and this VIII require some time though not
as long as to put it in place.
Is there any danger to the bridge While
/ the work is going on? Not bit The long
arches OF steel that support the driveway
/ Of the bridge do not now rest upon the pier
! at all, but are held up by massive trusses
/ Of timber which rest upon the Golfer
dam. The huge pier, sixty feet high, with
! its thousands Of tons OF stone might splash
! down into the Potomac and the bridge
! be none the weaker if the accident did
not carry a way the dam
What VIII the final cost of the repairs
/ be? The appropriation is SOL ,o7O, but
! it is likely there VIII be a deficiency