had blown itself out. They were several hundred miles away from the hostile warship, and there was not a vessel in sight on the broad expanse of blue ocean.
The air tanks were refilled, and after sailing along on the surface for an hour or two, the submarine was again sent below, as Captain Weston sighted through his telescope the smoke of a distant steamer.
"As long as it isn't the Wonder, we're all right," said Tom. "Still, we don't want to answer a lot of questions about ourselves and our object."
"No. I fancy the Wonder will give up the search," remarked the captain, as the Advance was sinking to the depths.
"We must be getting pretty near to the end of our search ourselves," ventured the young inventor.
"We are within five hundred miles of the intersection of the forty-fifth parallel and the twenty-seventh meridian, east from Washington," said the captain. "That's as near as I could locate the wreck. Once we reach that point we will have to search about under water, for I don't fancy the other divers left any buoys to mark the spot."
It was two days later, after uneventful sailing, partly on the surface, and partly submerged, that
