EPY. Here we are. Guard-boats will make mail-trip at hour indicated."
"All those other flags mean the hour," said Garth. "Mike, Yoke— What's a yellow flag with a round black spot in the middle?"
"Item," said Joan promptly; "I just learned it."
"There are some more," Garth said. "Numeral—Quack—Unit— Oh, there they go down!"
Joan laughed so hard that she could not look at the code for some minutes.
"Mike yoke item quack unit!" she gasped; "and you do say them so solemnly, Garth!"
After much searching through the signal-book, they came to the conclusion that the guard-boats would make the mail-trip at 8:15 a.m.
"And we mustn't forget to watch for them," said Garth.
"Do you really think they'll go?" Joan wondered.
When they looked up again, a single flag of yellow and black squares hung at the yard-arm of the Billington, Garth got to his feet suddenly.
