The red flag had been agreed upon as the signal to stop the fleet, when the navigation was very hazardous, or impracticable.
"Cease—rowing!" said Charles.
Frank ordered his signal man to hoist the red in the flag boat.
"Can't we go any farther than this?" asked Charles.
"I don't know; we are not more than a mile above the bridge."
"Here comes the Dip."
"Well, Tony, what's the matter?" said the commodore, as the tender approached.
"I haven't found a clear channel yet. The bed of the river is covered with rocks," replied Tony, as the Dip came alongside the Zephyr.
"Then we must call this the head of navigation," added Frank, with a laugh, though he was not a little disappointed to find the cruise up so soon.
"Perhaps not; there is water enough, but the twelve-oar boats are so long they can hardly dodge the rocks. The Lily and the Dart can get through very well."