question:  What did Don use as a method for seeing over the edge of the stream?
context: Radio messages stated simply that Superior had seceded from Earth. He backed up two hundred feet, set out flares, then sped off to a telephone. Communicating by radiophone across the vast pit, they confirmed that the town undoubtedly was missing. 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. Don Cort had been dozing in what passed for the club car on the Buckeye Cannonball when the train braked to a stop. When Don had entered the club car he'd seen her hatless head from above and noticed that the hair along the part was dark. Don made his way up to the locomotive and found a bigger knot of people gathered in front of the cowcatcher. Some sort of barricade had been put up across the tracks and it was covered with every imaginable kind of warning device. 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. True, everything seemed to stop, and they could see stars shining low on the horizon where stars could not properly be expected to be seen. 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. Nevertheless, Don could see that it apparently was a neat, sharp edge, not one of your old ragged, random edges such as might have been caused by an explosion. Standing on tiptoe and repressing a touch of giddiness, Don looked over the edge. 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.
output:  A compact from Alis.
options:  A mirror found in the Cavalier dorms.  A compact from Miss Jervis.  A compact from Alis.  A camera to take a photograph.