"We ought to be far enough south to strike the open polar sea which I believe exists."
The engine was started after the small leaks in the bow, caused by the ramming of the boat on the rocks, had been stopped up, and the professor, entering the conning tower, turned her due south.
The screw vibrated in the tunnel, the water rushed out in a big stream, the engines and dynamos hummed, and the hearts of all were lightened as they knew they were nearing the goal of their journey.
Several hours passed and the professor, who was keeping watch of the gages noted they had covered more than one hundred miles. As the supply of compressed air was getting low Mr. Henderson, not wanting to run any chances, decided to make an attempt to reach the surface and refill the tanks.
Accordingly the water tanks were emptied of their ballast, the rudder was set to force the ship to the surface, and soon the depth gage showed a constantly decreasing amount of water over the heads of the adventurers.
"Now, if we don't hit the ice above us we'll be all right," spoke Mr. Henderson. "We are within fifteen feet of the surface."
Hardly had he ceased speaking when the Porpoise brought up against something with a bump that jarred everyone. Then the submarine went scraping along, hitting the conning tower every now and then.
"Not clear of the ice yet," said Mr. Henderson. "We must go down a little and try again."
The tanks were filled with enough water to keep the boat about fifty feet under the surface, and at that depth she was sent ahead at full speed. The professor's face wore an anxious look, and when Washington asked him if it was not time to replenish the air supply of the boat the inventor told the colored man to be very sparing of the contents of the compressing tanks.
"I'm afraid we are not as near the open sea as I at first thought," Mr. Henderson finished.