"Wait a minute," ordered Lord Hastings. "You'll need this written order
to get the boat."

"I'd forgotten, sir," said Frank.

Lord Hastings scribbled rapidly on a piece of paper, which he passed to
Jack.

"This will fix you up," he said. "Now remember, 10 o'clock sharp."

The boys nodded their understanding of this order, saluted and left.
Getting their things together, they hurried to the river, where Lord
Hastings kept his motorboat; and an hour and a half later they were
proceeding slowly down the river.

"Guess none of the enemy will ever get in here," declared Frank, after a
careful survey of the river.

"Guess not," replied Jack. "Look at the boats. You wouldn't think we
were at war."

"Not if it wasn't for the warships," agreed Frank. "And there are enough
of them to make it hot for any hostile fleet. But it's a wonder to me
some of these German submarines haven't taken a little trip up the
Thames."

"Mines," replied Jack briefly.

"True," said Frank, "but you will remember we took a pretty long jaunt