"I have not yet made an exhaustive test of that," rejoined Mr. Barr, "but I estimate that we could remain below, if necessary, forty-eight hours."
"Forty-eight hours!" gasped Rob incredulously.
The inventor nodded calmly.
"My air purifying device makes this supposable. I have a plan by which fresh, pure air is almost manufactured. At the same time the foul air is forced out."
"I suppose you boys are aching to take a trip," laughed Ensign Hargreaves.
"Aching is no word for it," Rob assured him.
"Well, you may have a chance to-morrow," said Mr. Barr; "I am going to test out the whole craft thoroughly, and you boys can come along if I go."
For the next five minutes nothing could be heard but enthusiastic shouts. The boys fairly went wild with delight at the prospect of a trip below the ocean's surface. Soon afterward the party emerged from the submarine in time to see the Seneca making out to sea on her return journey. She carried letters from the boys to their families, as they were by no means sure when they would get the next opportunity of sending a letter north.
The next hour was occupied in making camp. Then the Stars and Stripes and the Eagle banner went up. Donald had no Wolf banner with him, but above his tent he hung up something that resembled a wolf's head, painted on a bit of canvas.
"Looks more like a chicken than a wolf," scornfully sniffed Tubby when he saw it.