 What action did Don consider for testing the water flow in Superior?
Radio messages stated simply that Superior had seceded from Earth. But Don Cort, stranded on that rising town, was beginning to suspect that nothing was simple about Superior except its citizens. The state police converged on the former site of Superior from several directions. The train's schedule called for it to pass through but not stop at Superior at 11:58. A National Guard officer volunteered to take a jeep down into the pit, having found a spot that seemed navigable. The object loomed out of a cloudbank at twelve thousand feet and Studley changed course to avoid it. One other radio message came from Superior, now airborne, on that first day. Don Cort had been dozing in what passed for the club car on the Buckeye Cannonball when the train braked to a stop. Don hesitated, shrugged at the redhead, said, "Excuse me," and followed the conductor. Don made his way up to the locomotive and found a bigger knot of people gathered in front of the cowcatcher. Don saw two men who must have been the engineer and the fireman talking to an old bearded gentleman wearing a civil defense helmet, a topcoat and riding boots. Don Cort and the fireman walked cautiously toward the edge while the professor ambled ahead with the familiarity of one who had been there before. He didn't have to stand on tiptoe any more than he had to sit on the edge of his seat during the exciting part of a movie, but the situation seemed to call for it.
 Taking a rowboat over the edge to see what would happen.
 Taking a rowboat over the edge to see what would happen.  Jumping into North Lake to see if there was an electrical current.  Swimming through the stream to see what would happen.  Throwing something into the stream and seeing if it would funnel back into Superior.