New-York tribune., 1875-10-13
WASHINGTON RING ENGINEERING.

replies. Is unanswerable. Af'
heir-Oriedns, Oct. L. 1873
WASHINGTON RING ENGINEERING.
THE NEW ANAcosTh IRON BRIDGE DISGRACE TO
THE GOVERNMENT
TO the Fdttor OF The Tribune.
SIR: The annual report Of Col o. f. Bab-
cock on the iron bridge the Anacosa branch OF
the Potomac, near Washington NavyIard has recently
been printed The bridge has been recently constructed
under his SUPERVISION and desire To call attention To
some very important facts in connection with thnt re-
port The following is abstract OF the description
and specifications for the bridge, published pIor to
its construction
The bridge consist OF Il spans Of lO2 feet each
and one draw o SO feet making the entire length of the
supersructurc 2G0 feet each span TO be composed
OF two iron Is feet hig iron beams and wooden
floors The width OF the roadway between the trusses
was to DO 20 feet aud two sidewalks were to be placed
outside each having width OF five feet thus making
the entire width OF floor surface 80 feet AS
the length was 102 feet, the floor area OF
each span would be 3,O60 square feet All
parts of the bridge to be propoltioned that
The maximum strain resulting from its own weight and
an applied load Of 100 pounds 10 the square foot OF oor
surface should not exceed onesxth OF the ultimate
strength Of hc iron. Hence the suffice 305O feet, null
tped by 100 pounds, gives The load for each span OF
5000 pounds. have no criticism to make Of the plan
of the bridge so far load and strength are concerned
They were lust what usually provided for in specih
cat, MS for common road bridges The specifications for
the foundations and masonry were also very good But
the work done does net in any respect correspond with
The requirements, and the C0.oncs report docs not prop
efly describe either the work. it has been done nor the
specincacnS while the test reported as having been ap
piled was wholly INADEQUATE
The Colonel says that "on the Goth Of June each and
every span the bridge submitted 10 test OF 532S2
pounds The detection produced by this load was not
pecepbe" That this assertion as to absence of dehcc-
ton cannot be true, any one may learn by standing
On Tie bridge while ordinary teams are passing He VIII
then see and feel too that the passing Of single
load viii produce such deeetions. both vertical and hor
zJntal as Will make the vbratory motion dsagreeably
"porccptble" An experiment Of this kind Will leave
doubt in the mind of any one that the application OF
SO 2S2 pounds must have produced considerable deee-
ton ANA yet that weight is but little more than one
sixth part OF The 100000 pound test load required by the
spccilcalions
Now why did the Colonel stop at that p0inl Why did
he not 20 on apply the full e5g or tr cfOurths Of
it, or a least onehalf Of the 100000 pounds instead Of
only about one-yth OF III The strain under full test
was not 10 exceed Oncsixh OF the ultimate strength OF
| the iron. Practical Lridgcbudcrs who understand the
business alter seeing the bridge viii readily answer the
foregoing questions by sayinS at the Colonel dared not
aupv the fil test load that tn bridge would certainly
have gone down under IT, proiaby Under ticcionttls,
seryrrs Vel understand that the fOotways of common
lrl Ices may occasionally become heavily ladrn with
u,an brng as the roadWays With ordinary traffic The
burning Of building or vessel In the licnlty aud
many other events may draw large crowds OF spectators
such circumstances and with the most appalling results
For i.ese reasons well-inormed engineers invariably
proylie as much strength for the fOOtTny for
c0rrcs sp0uding cXt,nt OF noor surface IN the road
Anacostia bridge 10 was Tor an 4ppied load OF 100
pounds to the square loot OF all the h09r surface.
! iIut for some unexplained reason which, how
ever a fair test OF the bridge would ny its
total failure have made quite plain. Col BabcOck has in
% NJ mart is cni,ai To- oncfii of fe whole pyeseribei
test Iosd and in rega"d to the roadway after applying
TO II the 2-2 pounds only about oneOurth par' OF the
test due to the roadway alone, ho makes the following
deceptive statement:
out. and 80 proportiohed In All lis parts That II the
every square foot Of surface ton ner lnca foot,
the bridge would be strained 10 only onefth OF lis ulti
mate strength"
But why does he say onc1ith." while the specinca-
ons require that the strain under the full load, ncud
inc that due 10 the footways shall exceed onesxh
OF the innate strength Of the iron If it Is true he
SAYS that due to the roadway alone woud bring
into equton only oneth OF the strength of the iron,
then why did he not apply that load. instead Of only
about fourth OF it-hat Is, about onesiNth of the
whole prescribed test load It certainly quite safe
test a bridge the extent of fifth Of IT'S actual
strength but test that stops at onethr!eth OF that
strength is little better than fgrco There ought not to
have the slightest danger In applying all OF the load
due To the roadway alone, that forms but tword5 OF
tie whole load The fact that there public notice
given OF proposed Of the bridge shows that it
not expected IL be be attended with very attcrng
suit, Everybody connected with this work las shown
great and suspicious anxiety 10 keep the dsgraccfu
truth in regard to ID from the public. aud offers OF money
lya actually been made to the writer OF this cOnnuni
catcn TO induce him not TO wfe anything about
the bridge the sham test OF its strength
and stability. rut, being practically well
| as scientifically familiar with the construction
and tra irg bgdges ana OF other WORK OF like charac
ter nd seeing the dangerous defects in this bridge feel
ii "A duty caution thc public against exceedingly
dan "a rolis fraud. am qnite willing 10 stake my pro-
cssonal reputation on the positive assertion that the
bridge cannot sustain the prescribed test that It's
strength falls fcaifuly short ON mat II by any means
one-laif that usual and reasonable test weight
be drawn upon side of the bridge In tc form Oi
human beings not improbable event under the before
mentioned circumstances, it VIII thenJertally down,
carving Wiih It, of course tie mass OF human beings
who mny have thus incautOuslY trusted their lives
that Government bridge constructed bY the Cove .nnent
King under the supervision of Government engineer
an army officer educated ut tie expense Of TIE people.
Can West Point afford 10 lot the cOndC, OF this Ocer 80
uunOtlccdf
Col. BGbcaeks report is aO shameiully erroneous in
regard to the foundations and masonry Of tie bridge.
The pilng is very defective The stone work under and
most Of that water Is OF the most inferior earc
ter all yielding, aud consdo rable portions OF It have from
time To time umbod down. The cement used Ia the
masonry Il. hardly better than street mud. one OF the
piers after being partially c0nstrc ed yielded much
as TO make II cossaFy 20 take 1t up and drive more
piles In its foundation OtEcr piers after being raised 10
thrir full hight, yielded and lcaned much thnt TO
prevent their falling they were taken down TO