The times. [volume] (Washington [D.C.]) 1897-1901, 1901-03-17

ing was perfectly controlled, and the Gals
son finally placed in its exact position
and perfectly vertical The internal spac
was then filed with concrete laid unde
water by the same bucket, and leveled b.
divers when necessary.
While this work was going on, the Gov
eminent of New South Wales in Australi
called for both, designs and tenders for
bridge over an estuary of the sea calle'
Hawkesbury. The conditions were tn
same as at Poughkeepsie, except that tn
soft mud reached to depth of 100 fee
below tide-level.
The designs of the engineers of TIL
Poughkeepsie bridge were accepted. ant
the same method of sinking open Gals
sons lin this case made of from was car
ried out with perfect success.
The erection of this bridge involved an
other difficult problem. The mud was too
soft and deep for piles and staging. anC
the cantilever system in this site would
have increased the cost.
| A staging was built on a large pontooT
at the shore, and the span erected upor
, it. The whole was then lowed out to tht
bridge site at high tide. AS the tide fell
| va P'"S'oh was io"eieu anu 'iiS a'ee
eiruer was placed gently on IT'S piers Inc
! "hoie operation was competed "ithiil SIN
| hours. Inc cther hVe spans were piaceo
| in the same manner
Inc same system was followed AFTER
ward by the engineer of the Canadian
Pacific Railway in placing the spans of a
| priose over the st. Lawrence, IN very
rapiu current. IL IS now USED IN replac-
ing OLD spans by new ones, as 1t interrupts
trainc Tor the least possible time
Inc solution of the problems presented
at Hawkesbury gave the second intro
uuc.on OF American engineers TO bridge
building outside of America. The first
was In l7s6, when an American carpenter
or shipwright built a bridge over Charles
River at Boston, lao feet long by forty
SIX feet wide. This bridge was of wood
supported on piles His work gained for
him such renown that he was called to
ireland and built similar bridge at Bel
fast
Tunneling by compressed air is hori-
zontal application of compressed air foun-
dattons. The earth is supported by an
iron tube, which is added to in rings,
which are pushed forward by hydraulic
jacks.
a tunnel Is now being made under an
arm OF the sea between Boston and East
Boston, some lio0 rect long and sixty
hNe ieet below tide. The interior lining
OF IRON tubing is not used The tunnel
IL puilt OF concrete, REINFORCED by steel
rous' Inns Will erect considerable
economy success In modern engineering
means doihg a thing IN the most econom-
ical way consistent with safety.
Inc 81 eiair tunnel which carries the
"raho trunk Fhaiiway OF Canada. under
'he outiet Oh LAKE Hufoh' Is successful
eAahiple Oh such pork- had the North
'uii"ei' a'Ne" 10TH peeI deslShed
'H 'Iu""! seieii'''' Piihcilles, 1t "ouiu
ftV'S nav oeeti i'iis"eu' WHICH 40"
~
ue'io'i vi r'P'o-transit fah-
ways "a 'i'iea 70 ano'her oiahSh ol en-
s' N0te''pS s'iu'tuiai' Heciieiii-
al anu 1ic'i' engineering. some Oh
,iieee IAN" az a'eu' anu are mere
''"eu''s' pu' 'iie iaNori'e type
"o 80 VI 'up""S'' i"ere are '"o
hi.uS' '.i'Se i'e"t iiie surface IKE 'he as
vi i-pnuoi' ''e suo"aSs IN
aiia' pei pil'i aup poston' anu that now
Duiiuins IN Ne" orA' Inc oou'h Lohdoh
anu 'ei'idi l-otoof' ana other LONDON
PIoJec's' are TUBES SUNK nity 10 eighty
iee' peio" 'he surface ana requiring eIe-
Nauors LOT aecess' 1hese are made on
pan ueNiseu pS- preathsau' ana consist
Oh cast-lroh tunes pushed Forward by ny
uiauic rams anu having 'he space out
Siue vi Tue 'uoe hiieu WIN iiquiu cement
PuihPeu INTO pace
Inc CONSTRUCTION oi 'he bos'oh subway
was diihcuit on account OF the small width
Vi the s'ret's' ther great trailc' ana the
necessity OF unuerpihhihg the foundations
OF buildings All oil TINS was successfully
zone without disturbing the trafnc Tor
a single day, ana reflects great credit on
the engineer OWING 10 the great width
OF New 1ork streets, the propiem Is SIM
pier III lhal respect put requires skill IN
uesish ana organization 10 complete the
work IN a snort time. Although many
tunes as iohS as the Boston subway IL
Will be punt In nearly the same me. The
design, where IN earth my be compared
to that OF steel once building twenty
miles long laid nat on one OF its sides
The redupllcation OF parts saves time and
labor and is the key to the anticipated
fapid progress. Near the surface this
SUBWAY Is Duiit IN open excavation, and
tunneiing Is confined tc rock
Ihe construction OF power-houses for
developing energy from coal and from
falling water requires much structural be-
sides electrical ana mechanical engineer
ing AFFINITY. me Niagara power-house is
intended to develop 10000 horse power; |
that at the Sault Ste. Marie as much; that |