There were great reaches of sand before them which trended upwards. That they ultimately rose above the surface in the form of a beach there was no doubt.
“We have reached the end of the isthmus,” declared Frank, “or at least that end which once joined the Cuban isle.”
“To make sure of it,” said Wade, “suppose we rise to the surface.”
Frank touched the tank-lever and the boat sprung upward. The next moment it was above the surface.
But all was darkness upon the sea. The hour was 4 A. M. and the sun had not yet colored the east.
But Frank turned on the searchlight and showed the cliffs distant not quite a half mile. That it was the Cuban isle there could be little doubt.
However, to make sure, the Diver lay-to off the coast until daybreak. Then bearings were taken. A small pearl-fishing sloop passed near.
Wade hailed it and learned for a fact that the coast was that of Cuba. Then he said:
“Let us go back to the deep sea. I ask only to follow the isthmus to the peninsula of Yucatan. All doubt will then be settled. My friend, Professor Brown, will then be very willing to admit his error.”
“He will if he is not pig-headed,” said Frank.
He was about to touch the tank-lever when Barney from the deck, gave a sudden sharp cry:
“Whurroo, Misther Frank, shure, it’s a sail off to windward!”
Frank and Wade gazed in that direction. Then both gave a violent start. A small schooner was seen bearing down upon the Diver.
“It is the Meta!” he exclaimed; “they are making for us!”
This was the truth. Hardy Poole’s piratical schooner it was, and they had sighted the submarine boat.
She was bearing down rapidly, with all sails set. Frank and his companions watched the schooner with some curiosity.
But Frank knew that it would never do for the schooner to come within cannon shot. One ball striking the submarine boat would be likely to ruin her.
So he ran up a signal flag of defiance. It was seen by Poole, and a cannon was fired in reply.
Then the voyagers skipped into the cabin and Frank sent the Diver to the bottom.
Westward now over the sunken isthmus her prow was turned. For hours she kept on.
Toward night the place where they had first descended was reached. Here a stop was made.
Thus far the trip was a glowing success. No serious mishap had marred the project.