El Paso herald. (El Paso, Tex.) 1901-1931, 1911-05-26

perpetual guarantee that 1.-THE dam
they are building is water-tight and
safe. With vast quantities Of water
on top Of the dam 1T is plain that If
there are any assures or other weak
spots the water will seek them out
and show them up. Here again the
wisdom Of the engineers has been vim
dicated--the material is more imperv-
ious to water than they promised il
should be. 1t becomes almost as hard
as concrete and forms = core that
water cannot get through. The nat
ural cement held in suspension by the
dredged water tightens up every tiny
space as a brick mason might close
a hole in a wall. One END of Gatun
dam Is now considerably higher than
half It's final height and The other end
is almost to the half way PORT.
The engineering problem Of Gatun
dam has been solved. The part of
the work which stiI demands the at
tertion of the engineers is the Gatun
spillway. The Chagres river Is
ms ody oil stream. Toby 1t will be
as gentle as a dove 30 SWALLOW aid
quiet that a boy of 10 could wade
across it; while tomorrow 1t may be-
come a torrential river with sus-
tanned flow of $4,000 cubic feet
second. How to build a spillway that
will pass such an enormous amount
to sea level without harming any de-
tail of the works was a problem
which called for the highest engineer
ing skill. It is true that Gatun lake
is so big that the Chagres could flow
into it for five hours and 20 minutes
while at its highest known stage and
still raise the level of the lake only
one foot; 1T also is true that the level
Of the lake may be increased seven
Oh -rrfT
damage. 1t thus will appear that
spillway accommodating less than the
maximum flow of the Chagres might
have met every situation the future
will bring forth.
But the engineers, with character
istic determination always to err on
the side of safety if at ali, are con-
structing a spillway over which more
water may be discharged than ever
has been known TO be brought down
by the Chagres river
Crosses Canal Line % Times.
The Chagres river now crosses the
line IF the canal % times on it's %
mile Quincy from Gamboa, at the At
lantic side Of Culebra cut. to Gatun-
When Gatun dam is completed this
entire section Of the river will be
wiped off the map. 1t will lose itself
in the waters OF the Gatun lake at
Gamboa. Even at its highest stages
ii will have comparatively little ef-
feet on the currents In the lake
The subway at Gatun viii have a
concrete dam of a crescent shape, sur
mounted by Is large piers and two big
abrtments. These divide the crest OF
the dam into IA openings. or bays,
which may be opened or closed indie
pendently Of each other by huge valve
eli al cd q a.
duce friction to a minimum Each of
these gates will be capable Of regu-
latfng the flow Of 1900 cubic feet OF
water After solving the problem OF
passing the water through the gates,
each of which is IS feet wide, the next
question which arose was how TO
check the current of the stream when
it went out upon the apron of the
spillway so as to prevent its doing
damage, Tor. unobssructed. the We
locity Of the water would be 35 feet
second. It was decided to build across
the apron of the spiilway two rows
Of BATTLE piers made of concrete and
faced on the upstream side with cast
iron plates 4 small model of the Ga
tun spillway has been placed in opera
ton and the practical results adhere
to those forecast by engineering the
DRY.
The dams on the Pacific side are COM
paratively unimportant The first one
encountered after passing through Gu
Zebra cut is that at Pedro Miguel It
will be approximately 1000 feet long
and will have head of only 45 feet of
water against it. 1t VIII have no spill
way to it, the surplus water being
cared for at the other end OF the lake
between Pedro Miguel and Miraflores
there will be a smaller lake, its W
ters imprisoned by two dams. with
crest of 30 feet. The dam from the east
side of the Miraflores locks TO the ad-
accent hills will be SEQ feet long. built
of concrete, and having on its crest
spillway capable Of discharging 10000
cubic feet of water a second. The 9TH