ave to swim for it if the boat is smashed,"
said Blake, who remained calm. "It won't be hard to do that. This
is like a big swimming tank, anyhow, but if they let the other
water in--"

He did not finish, but they knew what he meant. Slowly and
irresistibly the great lock gates were closing and now the tug had
almost been pulled back between them. She seemed likely to be
crushed to splinters.

CHAPTER XIII

IN THE JUNGLE

"What will we do with the cameras, Blake? The films, too, they
will all be spoiled--we haven't enough waterproof cases!" cried
Joe to his chum, as the boat, through some accident or failure,
backed nearer and nearer to the closing steel gates.

"Will we really have to jump overboard?" asked the Spaniard. "I am
not a very excellent swimmer."

But Blake, at whom these questions seemed directed, did not have
to answer them. For, after a series of confused shouts on the top
of the concrete wall above them the movement of the boat, as well
as the slow motion of the lock gates, ceased. It was just in time,
for the rudder of the tug was not more than a few feet away from
the jaws of steel.

"You're all right now," a man called down to those on the tug,
from the wall over their heads. "Something went wrong with the
towing locomotives. There's no more danger."

"Well, I'm glad to know that," answered Captain Watson gruffly.
"You might just as well kill a man as scare him to death. What was
the matter, anyhow?"

"Well, all of our machinery isn't working as smoothly as we'll
have it later," the canal engineer explained. "Some of our signals
went wrong as you were being towed through, and you went backward
instead of forward. Then it took a minute or so to stop the lock
gates. But you're all right now, and you'll go on through."

Blake and Joe looked at each other and smiled in relief, and Mr.
Alcando appeared to breathe easier. A little later the tug was
again urged forward toward the front lock gates. Then the closing
of those at her stern went on, until the vessel was in a square
steel and concrete basin--or, rather, a rectangular one, for it
was longer than it was wide, to lend itself to the shape of the
vessels. As Blake had said, it was like a big swimming tank.

"Now we'll go up," Captain Watson said. "You can't get any
pictures in here, I suppose?" he added.

"We can show the water bubbling up as it fills the lock," said
Blake. "Water always makes a pretty scene in moving pictures