The New York herald., 1878-10-25
THE SANDY HOOK BAR.

AN ENoIsEER's PLAN F'R DEEPENING THE
CHANNEL ABOVE 1.-THE JETTY SYSTEM
coNDEANED.
Mr.. Henry r. Knapp a civil engineer OF this city,
addressed the me embers OF the Produce Exchange In
the managers room No. SO Peart street, yesterday
afternoon, the subject OF deepe ming and straight
ening Tho channel over the Sandy HOOK bar Fabu-
ous ms. ho said, had been expended in attempts TO
prevent formation OF sand bars At the mouths Of
harbors, but failure had generally resulted from want
OF theoretical and practical knowledge of The sub
jeoL Engineers and scientists have radically differed
TO the cause Of such formations and the means Of
removing thom. Tho idea most generally entertained
Is that they arc the accumulation OF sediment de-
posted oy rivers they The speaker,
hswevsr, believed this idea to be erroneous
planned his own theory follows:-"At the mouth OF
every aud harbor debouchng into the there
exists two opposing forces II either were removed
the other would unimpeded sway either to
bar entirely away 70 completely shut up The mouih
The cause OF bar formation Is the action ol sca
YES on the bottom OF the sea heavng up sana ana
sediment into the mouth OF tho harbor and the only
thing that prevents Tho waves from closing up the
mouth Of every port is tho greater OF out
flowing current winch, II impeded In us exit by one
channel. will cut another. assp
A SUBMERGED BARRIER THE RgMBDr. @s.
"Wave action oeing the cause OF bar formation, II
only necessary 10 10 away with or modify such ac-
tion In order to deepen the bars; but this must bc
effected without In tho least reducing the capic'iy OF
tne mouth, or IN any way cammnn ap or impeding
Sandy Hook formation a submerged barrier or false
bar should be erected directly across Tho mouth OF tho
harbof the tsniathom curve on the outside slope
such q barrier, II was Claimed would not offer the
slightest impsdiment to the Tree passage Of Vessels
it's top wodld be about thirty. i've ieet below low
water. Neither would 1t impede the river current
into sea. Its apex would bs lower than The nat
ural bar. On the contrary, II would facilitate tho
and aid It to cut down the old bar. The posi-
OF the present herrsr from northeast to south
wes ana between It's ends and the shorsE there are
large spaces ior the currents from bon directions
sweep in ana prevent any settlement OF SAND or sed
imsnI THIS 10 an invaluabie feature, and ono that
GOULD be biaincd by jettes Who're inc lattor
have been ricd tor years past, they have mseraDly
failed At Port said, whore they were originally Of
great length and have been extended, The chan.
mel 10 open only by constant drcdgtng. and Tho
condition the Mas mouth Of tho Rhine,
where some fifteen powerful dredge boats were con-
unuousy work during the past year, AT expense
Of ST. 500 0O0 The results observable ~ the
mouth OF the Amsterdam canal, lately completed,
where piers, 5000 feat long. projected into
the sea, SO 10 form q large narbor.
THE BAssIN Ds CHAssE.
safer discovering that bencht derived from
jstiss the French government resortsd TO what was
called the .oassn dc ohasse' system. Expensive
in which the food tide
Is retained I'll the tide outside has fallen, wnen tno
gates opened and The rush Of water seaWard cuts
away the bar and deepens the channel This, how
ever, proved Intellectual ana the system has be-
come almost obsolete The Fronch government has
decided try entirely new plan invovin ng the
construction Of extonsve ARTIFICIAL narpor protected
by enclrcing jettiss." This plan, TOO, Mr.. Knapp
though would tail