The daily dispatch. [volume] (Richmond [Va.]) 1850-1884, 1884-03-13
TUMBLING THE BLUFFS.
A RARE WORK AT DUTCH GAP.
successful Experiment In Reducing the
Banks at this Place by Use OF Hydraulic
Pressure


Successful Experiment In Reducing the
Banks at this Place by Use OF Hydraulic
Pressure.
A notable event took place at Dutch Gap
yesterday. The bluffs on the sides of the
Gap have always been in the way OF vessels
coming around the bend, and from time to
time have been sliding down into the Gap.
| Various attempts have been made TO re-
move them, but as they are over fifty
! feet high the efforts were attended with
considerable expense.
! Somewhat over year ago Mr.. G.. =. l..
/ Burgwyn, the United States assistant en-
gineer, proposed TO Lieutenant- Colonel
William y. Craighill, Corps OF Engineers,
United States army, that he should be al
| lowed TO borrow some machinery belonging
/ TO the city OF Richmond, and make the eX.
pertinent OF reducing the bluff by hydrau-
lie pressure.
THE PUMP OBTAINED.
| Nothing resulted from this proposition
at that time. Later on the United States
| Government purchased pump for pre-
pairing the way for the divers by pumping
the sand and mud of the solid rock where
the divers were setting the drill-rods.
Thus Mr.. Burgwyn got control of the
necessary machinery, and the proposition
was again made to Colonel Craighill. who
now consented that the experiment should
be tried whenever the occasion was fitting.
WAITING A FLOOD.
II was calculated that the detritus
brought down would be so great that a
current OF four feet per second would be
necessary to carry it all of into the deep
7 hnl Yrg hol n A. tha x-nln
Of an ordinary ebb tide through the Gap is
only about three feet per second, the
pl oper occasion could only be obtained
when there was freShet in the river.
( The heavy rains that fell last Saturday and
Sunday gave the very opportunity wanted,
and accordingly the machinery was towed
to the Gap and got into position as soon as
the water began running.
At first there was but little indication OF
the effect, but very soon the powerful
stream began to work.
DIVER TAKES A HAND.
The strongest Of the divers was encased
in an old diving-suit and held the nozzle
against the bank. The first force of the
stream knocked him down, but he got up
and lashed himself with ropes and then
forced the nozzle within few feet of the
bank. After some minutes the water be-
gan cutting away sand, cobble-stOnes. and
what boulderS there were; then the entire
bank began to undermine, and as fast as
the water would cat away the toe Of the
bank the superintendent mass would
tumble down. This was caught by the
powerful current in the Gap and forced
into the deep hole and entirely across the
river on to the Chesterfield shore.
TREES TUMBLE.
Finally large trees would undermine and
wash out.
The tug-boat put line to one tree and
| hauled it into the river, but as soon as the
current caught it. tree, tug-boat, and all
were carried through the Gap, and when
the tree was hauled upon shore below the
Gap it was stripped of all the earth usually
cinging 10 the roots. AS the stream cut
its way further into the bluff greater
quantities OF earth would come down at
once.
| WONDERFUL EXPECTS.
To one who has moi witnessed the eff
| fectS it hardly seems credible that such
great results could be reached by so appa-
rently small force.
| The reason OF it is that the tremendous
/ forces of nature were also working with
! the engineer.
| As soon as the stream cut away the sup
port to the bank, gravitation came in and
| took down the large mesScS, and as these
were carried into the swift, current il caught
/ the finely-divided particles up and forced
them across the river.
On account Of the peculiar topography
of the place the current, when strong,
goes across the river, and hence the detri-
tus is carried out OF the way.
THE WORK OF TWO HUNDRED MEN.
! Ii seems q pity that the city could not
/ have given Mr.. Burgwyn. for the James
River Improvement, the Hollywood steam
pump, instead Of selling it as old Junk.
The price paid for it by the iunk-dealer
was less than 5000; and as it is about ten
times as powerful as the one now being
used, results would have been obtained
proportionally greater.
| Ii is estimated that even the present
pump has moved in one day as much ma
terlal as 200 men could handle in the same
| time.
THE FIRST INSTANCE.
Were the powerful pump that supplied
the CITY with water at the old works also
available for this purpose, it would not
take long to cut the bluffs sufficiently away
for all practical purposes.
1t has been state d that the cutting down
OF Dutch Gap by the hydraulic method is
the first instance of its practical application
on large scale east OF the Mississippi.
GREAT POINT GAINED