New-York tribune., 1873-05-10
THE WASHINGTON RING.
rrc n, ,rUnpps TN ENGINEERING.

DANGERS OF TNUNDATIONS-THb CaNnb syxvpp
FAILURK-FooLIsH EXPENDITURE foh o""'
PIPES. .r
To me Rdtfor Of The Tribune
SIR. Much time seems to me to nave peeh
wasted over the chaotic and utter worthless 81"
Of tho Board Of Public Works. in tho searcn ioi .u
tian touebing the financial condition OF the Guy NJ
that appears TO have been gained is the certanV
millions OF dollars raised by the city ana 'o'ou
gress has in way disappeared ioa''ne
teachers policemen, fremen, and numerous
with unpad bills amounting in the aggregate 70 n''C"
y, more Ono other thing the people are pegih-
ming TO find out from the study Of the numerous
reckIess and contradictory statements OF the noaro' ~
from All examination OF their wretched work eaiieu %
provemens aud that is that its members are Prossy
ignorant of the fundamental principles pertank "
improvement OF cities. -. Z,
For the purpose Of exhibiting some OF ther
tbe consequences resulting from them VIII Degn "'n
the part of their report relating 20 the main Se"o'
published in December. 1872; and in order tna' "a
follows NAV be understood quote tho following eA'rac'
from the report OF the Board; ,.,.
The sewerage of the city had received ou. nf nes,
attention prior TO the inauglTati1mp mstrict large
proportion OF the drainage enpled INTO an ater de-
known the canal. Inc calTtme tbe tides ~ in the
river was insufficient carry OF the deposits hue % az
the outlets of the various sewers and the caa o' m
came so offensive as 10 threaten pestlehCe anu W.
slightly AZ TO disgust every beholder. -,
The plan OF the city rendered an lhterseot,,
b brS1sS sewers from the northern part Of the city
had been led into the canal AItSr naV ta w. I,,iId
liberation and consultation. t was concluded 10 Dnlu
an intersecing sewer from Seyenth-s west 10 sever
teenth-st west, following course pIsel W ser nu
canal and from Sxthst west TO Tbrdst. West-Io @
braneb erpptyng into the river at Seyenteenths anu
The latter into the Tber arch Thirds These sewer.
vapY IN Size from TO IL feet in diameter, increasing
~ as they approach their outlets. in order
TO obtain free and unobstructed discharge The work
on these improvements is nearly compieteu no oats
a ed and
warrants the Board in expressing the opinion 9
that the problem which has so long 5 ui5
tnTbed our citizens has been successfully sOyeI
: Reference has been made to the IlDer creek
seVer which receives all the sewerage OF the city east
f sitbst eat and drains "a section OF country nOIlh
ward embracing an area Oi more thah oODV t, hnU
only portion OF this sewer TnGn nu h en arch
PcnnsyIvanIa- and passing through the Botahea
Garden far as ThTdsS west. tnS az T6irdst
across Maryandave., and northwardy Irom tne , no,
side Of PennsylvanialVe.. ioloWlnk tno Mn
oourse TO Est north at its junction with NOIth CdPo
ST. where IL diyerged 10 the center OF NOth I'P.
This Is one Of the largest IN h ,9 To he
of abundant capacity 10 supply All the ueulaIius n
upon it, The floods Of the past summer n, has oo wpSon
impaiY1ng its strength or soidItY Ia the 'hgne''
u's'oe tussr ,1E,rESrs OF SEWER MEASUREMENTS.
Tho Boards statement that the B-st sewer along the
canal between Seventh aud seventeenthsts, has d.
ameer varying from five 10 twelve feet Incorrect
The mistake arises from confounding diameter WIN
spau The term diameter only be properly applied
TO circular sewers span means only the horizontal ex
tent of opening the deph, which may be equal 10
the span much more much less 1t will thus be seen
that the sectional or capacity cannot De oeter-
mined by the span alone. The Bst sewer is In fact,
datbotomed and arched. The span of its largest part
feet and its depth such to make the area OF It's
cross section 92 square feet or 24S feet less than the
area OF circular OF IA feo diameter as tho Board
have represented It TO he. In another part OF the same
report they speak OF the span such manner as to
the idea that its width Is uniform not reduced to
five feet the smallest end. as they represent the d-
ameter TO De reduced Finally they give the length OF
the sewer $500 feet which is more than 200 feet than
it really is Altogether these statements form strange
ly unbusinessliKe medley Of errors and absurdies.
What the Board says Of tho Tiber sewer is still more
incongruous They first represent 1t as having diane
ter varying from "a TO 80 feet This would give II sec
ona OF TOO square feet in It's largest part But TINS
sewer too Hat arched structure, and its actual ca
pacty is only 235 square feet less than onethird Of
the 7O6 feet the Board represent 1t to be- by assigning TO
il diameter Of 80 feet In another place they represent
as having span Of 30 feet If the report with It's loose
and random statements were placed in the hands OF
any competent engineer who had no other Information
about our than might be gathered from 1t. he
would utterly unable TO ascertain the size or capacity
Of any OF the sewers what they ought to be- or to de-
whether Board should pay for constructing
sewer for the Tber OF 255 feet or OF 7O6 feet capacity
THE SEWERS INADEQUATE IN TIME oP FLOODS.
The Board also make the astounding statement that
the floods OF the past Summer Qs70 have equaled any
ON record aud concluded that the capacity aud stab
y OF the have been amply proved as they have
stood the test of foods without having their strength
or stability impaired in the slightest degree. Unfor-
unatey for the Board this assertion is not true. II ~
at variance with former statements Of their own, with
meteorological records and with facts OF general OBJ
servation During the observation OF 1872, A. B. Null
lett then Chief Engineer of the Board. reported page
t that the heaviest fall OF rain record had not
eeeded two INCHES an hour and it s fact that this
amount has been recorded at the Smithsonian Insttu
ton. The heaviest rain OF 1872, that OF Sept 49,
amounted to only 249 inches IN 2i hours, which is
small fraction less than inch hour to be exact
o6 of an inch. II will thus be that Mr. Muetts
report written In December 1871 and the last report Of
the Board made in November, 1872, widely at va
rance Every resident OF this city knows that during
the past year there been great flood to test the
But although the rain Of last September did not
on account Of its short duration, food 1t did
produce freshet Of considerable magnitude and con-
rary the OF the Board it proved con-
eusveIy that the capacity of most of the is
very far from being adequate. The water not only
filed the lower part Of the Tiber arch 10 its full Ca
pacty but sOhgh as 10 issue from its manhoes on
It's crown and flow the surface at elevation OF
about eight above the level OF the river that time
And south OF present terminus OF the arch at Mary
andave., the water formed great lake, with is sur
face nearly on level with the Of the arch. These
facts prove conclusiyely that great flood would be
likely to break up some of the weakest parts of the
arch-probably that within The Botanical Garden-and
to extensive inundatons along the valley OF the
canal And this danger would be greatly increased If
the arch should be extended further southwark
say the tide level that OF the part between
Missouri and Marylandayes., constituting the ex-
tension the Board have proposed to do see Report
of the Investigation. page IA.
RAyAGEs FREsHETs
The freshet already referred TO deeply submerged the
Missourave. II delnged all OF the cellars and
Easements connected with it, far north Sixth and
seyenthsts and Pennsylyanaaye At Sixth-st and the
the water issued from the manholes with such