It was a splash in the water.
At first Frank instinctively thought of the presence of some submarine monster, but recollection came to him in time.
“Tony!” he cried; “is that you?”
“Thank God!” was the reply.
Neither could see the other, but they swam side by side in the darkness.
“Thank Heaven, you are alive!” said Frank, sincerely. “I feared you were dead.”
“I am alive,” said Buckden, “but I fear we will never get out of this.”
“Why did you not answer my call?” asked Frank.
“I did not hear it.”
“Is that possible?”