crete walls," pointed Bert. "Fifty-two
feet thick!

"Well, twenty-five million dollars will do a lot, and I've read that it
cost that much for these locks alone. And that's only a fraction of the
entire work."

At every turn, they came across something that evoked their wonder and
admiration. Most of the figures and statistics connected with the
colossal work they were already familiar with, but the information thus
gained was, in a certain sense, hazy and unreal. It was seen through the
mirage of distance, and not until their eyes actually saw the work in
course of construction, did the knowledge lying in their minds, take a
sharp and clearly cut outline.

As they moved about the dam, they came in contact with many of the
engineers connected with the work. These were picked men, Americans like
themselves, and of the very highest class of skilled engineers. They
were glad to meet the young fellows from the States--"God's country," as
they named it to themselves, in moments of homesickness--and the
intelligent interest of the boys, in marked contrast to many of the "fool
questions" put to them by the general run of tourists, made them eager to
impart to them all they wanted to know. They grew "chummy" at once, and
by the time the boys had spent a half a day in their inspection, they
knew more about it than they would have gained in a month of reading.

Among other things, they learned that the locks were the greatest
reinforced concrete structure in the world. They had been built in
sections, thirty-six feet long, and these had been joined together so as
to make one gigantic rock, thirty-five hundred feet long and three
hundred and eighty-four feet wide. This reached down fifty feet under
tide, and towered one hundred and fifteen feet above the level of the
sea. The concrete necessary was brought in barges that if strung along
in one tow would have stretched from Colon to the southern coast of the
United States, a distance of fifteen hundred miles. Great masses of
steel were first erected, and then the concrete was poured into these by
giant mixers.

The wall at the west wing held back the waters of the Chagres River.
This was allowed to spread out into a lake, covering nearly two hundred
square miles, at a level of eighty-seven feet. From this the water was
drawn to feed the locks, and even in the dryest season would prove
sufficient for that purpose.

Then there was the great spillway, in the hill th