The evening world., 1904-06-15
Sinking Of the Last Piece for
/ fhe Subway Under the Har-
lem Successfully Accom-
pIlshed'by D. D.. Mclean.
tkTEST METHOD OF
TUNNEL CONSTRUCTION.
dWln Tube About Six Hundred
and Forty-five Feet Long Now
in Position-HoW the Work
Was Done. 50

kgnssssnHtrg of the last section OF tho
bnnai under the Harlem River near
banox avenue was successfully accom-
nished to-day. The method OF con-
ktructing and sinking was an inuova-
Hon in tunnel work, and the credit OF
The achievement belongs to D. d. Nc
Bean, of the firm OF Mc1tullen 6 Mo-
Rean.
g Heretofore the method pursued IN
funnel work under rivers has been the
! usual one OF boring underneath and
constructing beneath the water. MT.
lAfcBean's scheme was to build a thn-
mel on dry land and then sink 1t IN
,place and finish It afterHard.
The hour set for sinking the tunnel
WAS 9 A. NJ, as at that hour tile tide
Has at its lowest ebb and less time
would be consumed in sinking II. but
although the worhingmen were on hand
Il was not until $50 O'Clock that the
siuirfng process actually began. AT !
S'clook the top Of the tunnel was sven
with the surface OF the water INC at
noon Il rested on the bottom.
sig weeks to Finish Work.
n will take about six weeks TO finish
rRhe work, as there arc yet about 300
East of the subway to be constructed.
). Tn section sunk to-day vas the
middle span. The other two sections
pn either side have been already nm
jlshsd by the usual old methods.
J Ths entire tunnel. with tho sunken
pectaon of to-day included. Is a twin
tune, east-iron tunnel about $40 feet
long.
The nrst half OF the tunnel. from the
,ul,ors TO the middle OF the river. was
butt under pneumatic pressure In a
laatsson. Underneath the roof OF this
Iraisson the excavation was completed,
enc cast-iron she'll was assembled ana
ixhs concrete was placed.
when Mr.. Mclean decided on his re"
Ssdea ne Immediately set about carry
ItnR It into execution. He caused O
ISsmporary ptle-deck TO be constructed
, Arom the shore 10 tho completed IAN
Or the tunnel. inclosinG n space thirty
nine feet wide and three hundred ieel
tong, inclosing the tunnel.
Permanent Foundation Piles.
Rows OF permanent foundation piles
were driven here as required. and these
AuDDOIItu llbll ~ 80
frame. which served as guides for tho
accurate alignment of the sheet piles
Of the sidewalks.
After the piles had been braccd and
cut off under water a p%ontoon ID feet
wide. IO5 fest Ions and l. feet deep was
built over the centre line of tho tunnel
nc the shcre, between the construction
dock. on the floor of this ponloon were
laid transverse timbers eight feet apart.
and on them were laid a row OF longi-
tudinol timbers. Between these the
plank flooring was spiked TO the under
lying transverse tiInbCrs.
Access was provided TO tho interior by
arranging segments of the shell-plate.
so that they could he unOoltel and
removed. Exterior concrete was then
nlied over the shell, virtually complei-
Ing the upper half OF the tunnel. The
work of finishing the lower hall OF the
tunnel will be done after ule conl'G-
lions have been made with the otl"r
two sections IN the tunnel proper
pumped dry. The TUNE now. or course
q hiled with water, which VIII Ie
pumped out after connections are made
at either end OF the section sunlSen to-
day.