200 
THE NATIONAL GEOGRAPHIC MAGAZINE 
criticism of it today is that it is still 
larger than was necessary. Colonel 
Goethals admits that if he had been 
building it for private corporations he 
would have made it smaller. But "con- 
cede everything else to safety" has been 
his policy from beginning to end. 
We see this same attitude in the mat- 
ter of providing for the disposal of sur- 
plus water coming into Gatun Lake dur- 
ing the high stages of the Chagres River. 
The Gatun spillway is being built so that 
it can discharge 137,000 cubic feet of 
water a second, the water issuing at a 
speed of 35 feet a second. 
This will take care of the maddest 
flood that history records in the Chagres. 
In addition to this, the big culverts of 
the locks can be turned open and a flood 
of 170,000 feet a second is provided for. 
Yet the Chagres can flow at its highest 
known stage into the Gatun Lake for 
5I/2 hours, with no discharge at all. and 
raise its level only one foot, and can 
raise seven feet without doing damage. 
In other words, although the Chagres 
could do its worst for a day and a half, 
without a drop of water going over the 
spillway, without doing any damage, the 
canal authorities have arranged to pass 
out more water per hour than the Cha- 
gres can possibly bring down, and have 
not presumed at all upon that day and a 
half advantage over the Chagres. 
DVURY continge;ncy provided against 
Still another incident serves to illus- 
trate the wonderful care that has been 
taken uniformly not to draw a rosier 
picture than conditions warrant. Colo- 
nel Goethals always declared that the 
material which would constitute the hy- 
draulic core of the dam would be suffi- 
ciently impervious to water to prevent 
any dangerous seepage. But experience 
is proving that there is no seepage at 
all. A long pond is maintained at all 
times on the crest of the dam, and into 
this the big dredges are pumping mil- 
lions of gallons of water. The clay set- 
tles and part of the water runs off. The 
remainder stays there, seeking out every 
possible crack and crevice, a sort of hy- 
draulic stone-mason, who tightens up 
every minute space and offers a perpetual 
guarantee that when he finishes his work 
all will evermore be well. 
Another illustration, showing how 
more than cautious are the responsible 
heads of the canal in their efforts to in- 
sure its integrity, is the provision against 
accidents in the operation of the locks. 
The fact that they are, so to speak, 
"double-tracked," so that even if things 
should go wrong in the one set of locks, 
the other set will be available, is in itself 
regarded as practically eliminating dan- 
ger. But this is only an incidental pre- 
cautionary step. 
In order to guard against danger from 
a ship ramming the upper or lower 
gates, there is a heavy chain stretched 
across the channel, with the ends at- 
tached to giant hydraulic paying-out 
machinery. These chains and their pay- 
ing-out attachments are strong enough 
to stop a 1 0,000- ton steamer traveling at 
the rate of five knots an hour. But even 
if they should fail to bring a vessel to a 
stop and it should ram down the outer 
gates, there would still be a second pair 
of gates across the channel. Not once in 
millions of times would the first gates 
be rammed, and as for the next pair, it 
is almost beyond possibility that they 
should be reached by the vessel and 
forced open. 
But suppose the chain failed to stop 
the ship, then that the outer gates also 
failed, and then even that the almost im- 
possible should happen — the second pair 
of gates rammed : even that contingency 
is amply provided against. A large canti- 
lever bridge will be ready at all times to 
be swung across the channel. From this 
there would be let down a series of 
nickel steel wicket girders into the madly 
rushing waters. The lower ends of these 
girders would engage a sort of offset in 
the lock floor, making a series of small, 
nearly perpendicular railways, on which 
large steel sheets mounted on rollers 
would be let down. By the time all of 
the girders and sheets of steel were in 
place, there would be an effective steel 
dam interposed to replace the damaged 
gates. Such an emergency dam is to be 
found at the Soo locks. Although it had 
grown so rusty by disuse that it could 
not be operated by power when an acci- 
